Human birth is supreme amongst all life forms as it provides an opportunity for the soul to end its journey of births and deaths and merge in God. For this the humans must realize what they are here for and conduct their life accordingly. This is taught by the scriptures which are Sri Guru Granth Sahib and compositions of the tenth Guru for the Sikhs. The compositions are called Banis.
The Sikh Reht Maryada (Code of Conduct) has laid down Banis to be recited (called doing Paath) in the morning, evening and at bedtime. They have been so chosen as to facilitate a spiritual householder’s life. This means doing our mundane duties but setting aside time to remind ourselves of the purpose of life and inevitability of death. The practice of Nitnem facilitates remembering God; as also en ableing breaking away from activities and thus avoid worldly attachments. This also clarifies the concept of ‘avoiding worldly attachments’ or Moh frequently advocated in Gurbani. Guru Nanak explains the need for doing this:

ਜੋ ਦੀਸੈ ਸੋ ਆਸ ਨਿਰਾਸਾ ॥

ਕਾਮ ਕ੍ਰੋਧ ਬਿਖੁ ਭੂਖ ਪਿਆਸਾ ॥

ਨਾਨਕ ਬਿਰਲੇ ਮਿਲਹਿ ਉਦਾਸਾ ॥੮॥ ੧ ੨੨੪
I find every one filled with desires or disappointments:
Every one is in the grip of desires, wrath and craving (for mammon);
Rare ones are those not attached to these (M: 1, p 224).

Gurbani exhorts us to remember God with single minded attention:

ਪ੍ਰਭ ਕੀ ਉਸਤਤਿ ਕਰਹੁ ਸੰਤ ਮੀਤ ॥ ਸਾਵਧਾਨ ਏਕਾਗਰ ਚੀਤ ॥ ੫ ੨੯੫

O my holy friends praise God;

Do it with alertness and single minded attention (M: 5, p 295).

Doing Paath to praise God is establishing communication with the Divine. If we can perceive the Lord to be present with us it creates a zeal for communication. The third Guru says:
ਸਦਾ ਹਦੂਰਿ ਗੁਰਮੁਖਿ ਜਾਪੈ ॥ ਸਬਦੇ ਸੇਵੈ ਸੋ ਜਨੁ ਧ੍ਰਾਪੈ ॥
ਅਨਦਿਨੁ ਸੇਵਹਿ ਸਚੀ ਬਾਣੀ ਸਬਦਿ ਸਚੈ ਓਮਾਹਾ ਹੇ ॥੮॥ ੩ ੧੦੫੫

God’s presence is perceived through the Guru’s word:

One who thus serves the Lord feels satisfied;

He then ever dwells on the Word and is enthused (M: 3, p 1055).

If we understand the Shabad and love it, we are enthused to recite or sing it. Without proper understanding Paath remains mechanical recitation. Guru Nanak explains:

ਜਿਨਿ ਕਹਿਆ ਤਿਨਿ ਕਹਨੁ ਵਖਾਨਿਆ ॥

ਜਿਨਿ ਬੂਝਿਆ ਤਿਨਿ ਸਹਜਿ ਪਛਾਨਿਆ ॥

ਦੇਖਿ ਬੀਚਾਰਿ ਮੇਰਾ ਮਨੁ ਮਾਨਿਆ ॥੬॥ ੧ ੨੨੧

One, who just says, only keeps saying;

he who understands, experiences the Lord easily;

this seeing and experiencing is satisfying for the mind (M: 1, p 221).

However there are impediments to concentration resulting in distractions, yawning or even drowsiness. These

may be due to one or more of the following factors:

• Insufficient sleep.
• Rich food.
• Overeating or being famished.
• Making effort to concentrate.
• Physical fatigue.
• Some strong desire.
• Thoughts of past events or future plans.
• Being in a conflict situation.

The remedies for the above are evident. Instead of making effort to concentrate one should relax the mind. It is not easy to control the mind in case of the last two but knowing why we are reciting a Bani and what it means is helpful in keeping distractions at bay. Conflict situations may be helped by the prayer. The tenth Guru prays:
ਨਮੋ ਕਲਹ ਕਰਤਾ ਨਮੋ ਸਾਂਤ ਰੂਪੇ ॥ ਜਾਪ, ੧੮੭
My obeisance to One who creates conflict but is the embodiment of peace (Jaap, 187).

Thinking on these lines motivates one to realize if he/ she himself/ herself is the cause for the conflict, its continuation or exacerbation.
The method of recitation is important as proper recitation not only gives satisfaction, the body and mind participate in the process.
Recitations should be done matching with the breathing rythm. This helps in the speech, body and mind working in unison. This way the reciter neither gets out of breath as in a fast recitation or/ combining sentences (Tuks), or the mind wavering if the reitation is too slow.
A devotee who has achieved success in concentration can probably be in a posture for a long time without feeling the strain. The general prescription however is:
ਮਨ ਮੇਰੇ ਸੁਖ ਸਹਜ ਸੇਤੀ ਜਪਿ ਨਾਉ ॥ ੫ ੪੪

O my mind remember the Divine virtues naturally and comfortably (M: 5, p 44).
Along with the need for coordinating recitation with the breathing, the meanings of the Tuks need to be kept in mind. For this purpose it is helpful to give a break (Vishram) between Tuks and some times the Tuks should be broken down into two or more parts. The examples below demonstrate this:
Tayra keeta jaato naahi – mainu jog keetoee (Rehras)
Sometimes many breaks may become necessary; they come automatically if the recitation is understood. The reverse is also true; if thus recited the tUk is easily understood. Here are few examples:
Tu Karta sachiaar – mainda saaee;
Jau tau bhaavai – soee theesee – jo tu deh – soee hau paee (Rehras).
Kavav so vela – vakhat kavan – kavan thit – kavan vaar;
Kavan se ruti – maah kavan – jit hoaa aakaar (Japji).
Des aur na bhes jaakar – roop – rekh – na raag;
jatr tatr – dis visa – hoe phaileo – anuraag. 80. (Jaap Sahib).

It is helpful to perceive a vibration going down the body, from the tongue to the lower stomach as we recite.
At times when the situation is more adverse concentration becomes easier if we recite every word deliberately separated from the last. This also helps in undersatnding the recitation.
The one single factor helpful in achieving concentration is deflation of the self (ego) as when making a supplication. In other words Nitnem should be done in humility or Nimrata.
Understanding of the recitation creates interest and one feels motivated. Going a step further, interest is further enhanced if it is understood why a particular Bani is recited at a given time.Understanding the purpose of each individual Bani also helps in being aware of of the recitation. In this regard we may look at the five Nitnem Banis thus:
Japji Sahib.
This is in the form of Updesh or instruction to the mind. So it needs to be recited to the self and not primarily meant for others to hear, which they may do. If this is kept in mind it should be possible to identify ego or any other distraction. Japji Sahib conditions the mind to be receptive.

Jaap Sahib.

This Bani of the tenth Guru is entirely in praise of Akal Purakh either in second or third person. In the former portions, it should be possible to detect whether the reciter is talking to the Master or not. Somtimes evil ideas tend to come to mind during Paath. These pertain to something that has happened or is to be done. If such a thing happens one may tell the self “so this is how you talk to the Lord’? The course may then corrected. Of course this is applicable in respect of all Banis.
Swayyay.

These ten Swayyas are the last composition before we take on the mundane activities for the day. They tell us not to get too engrossed in making money, unjust exercise of authority and the like. The ninth Swayya tells us to avoid pretense and act in love (Jin prem keeo tin hi Prabh paaio). Understanding them as such makes them interesting and helps in concentration.
Rehras Sahib
This is recited at sunset after the day’s work is over. One may be tired, elated or not so happy because of what happened during the day. The compositions forming part of Rehras are meant to thank the Lord for enabling us to do our duties that day. It is mostly in second person addressed to God. The day’s distraction and fatigue may make concentration difficult but it helps if the mind is motivated that it is going to talk to the Master. Its beginning lends itself well for the purpose. It starts with “Sodar tayra kihaa –“. Later “Vaday mayaray Saahiba –“, Tu ghat ghat antar –“Tu karta sachiaar maidaa saaee”, “Na hau jatti satti nahi –” all in second person. These are only representative examples. Similarly in the Chaupaee the tenth Guru enables us to talk to Akal Purakh in large part e.g. “Hamri karahu haath day rachhaa”, “Tumhay chaad koee na dhiaaoo”, “Raakh lahu mohay raakhanhaaray” and so on.
Sohila
Sohila to be recited at bed time is a short Bani reminding us about the end of life both by itself and a metaphor for end of the day. If recited in that spirit, it brings humility and concentration folowed by good sleep.