Kirtan is a mandatory rehat to increase ones bhagti; kirtan is the highest karam in Kaljug.
ਕਲਜੁਗ ਮਹਿ ਕੀਰਤਨੁ ਪਰਧਾਨਾ ॥
In this Dark Age of Kali Yuga, the Kirtan of the Lord's Praises are most sublime and exalted.
Bhai Randhir Singh Ji refers to Kirtan as ਸਿਰ ਕਰਮਨ ਕੇ ਕਰਮਨਾ ਹੈ- Supreme Karam of Karams
Bhai Sahib states the following
ਸਿੱਟਾ ਇਹ ਹੈ ਕਿ ਕੀਰਤਨ ਗਾਵਨ ਰੂਪੀ ਸਿਫਤਿ- ਸਾਲਾਹ ਕਰਨਾ ਹੀ ਪੂਰਨ ਗੁਰਮਤਿ ਗਿਆਨ ਹੈ। ਯਦਿ ' ਹਰਿ ਕੀਰਤਨ ', ਸਿਰ ਕਰਮਨ ਕੇ ਕਰਮਨਾ ਹੈ, ਆਰਥਾਤ, ਮੁਖ ਬਿਬੇਕ ਕਰਮ ਹੈ, ਤਦੇ ਹੀ ਹੁਕਮ ਮਿਲਦਾ ਹੈ ਕਿ ' ਗਾਓੁ ' ਇਹ ਕੀਰਤਨ। ਯਦਿ ਅਜਿਹਾ ਮੁਕ ਕਰਮ- ਬਿਬੇਕ ਹੈ ਇਸ ਕਰਮ ਦਾ ਬਿਨਾਸ ਤੁਰੀਆ ਪਦ ਵਿਕੇ ਭੀ ਜਾ ਕੇ ਨਹੀਂ। Bhai Randhir Singh Ji
According to Bhai Sahib this karam of Kiran does not even end in the highest state turiya pad. How wonderful would it to be in a state on never-ending kirtan? WHere never ending kirtan becomes our sole sustenance?
ਅਖੰਡ ਕੀਰਤਨੁ ਤਿਨਿ ਭੋਜਨੁ ਚੂਰਾ ॥
ਕਹੁ ਨਾਨਕ ਜਿਸੁ ਸਤਿਗੁਰੁ ਪੂਰਾ ॥੮॥੨॥
Kirtan makes one fall more in love with the Gurshabad. Try doing kirtan with sincerity and emotion then do nitnem or any paath rite afterwards and see the difference for yourself. Even if you dont know how to do kirtan on the vaja you should still do it with your heart or mind as this too still counts. Also going to sangat and singing and listening to kirtan is of paramount benefit. Without these acts the seeker does not reach far in Bhagti. Personally I dont know how to do kirtan properly since I have no formal training but I do feel its important to give it a try. you dont need to be a musician or have a perfect voice to do kirtan all you need is a heart and devotion. The more practice of kirtan the more devotion we build up. Naam Abhyiaas, Gurbani Paath, without Kirtan is incomplete rehat.
There are so many thing Bhai Gurdas Ji says about kirtan in Sadh Sangat I would suggest you read these verses privately.
Just to clarify kirtan is not a personal choice but a requirement for every Gursikh since its Guru Jis Hukum. It helps but you dont need a vaja to fullfill the requirement of doing kirtan. Going to Sadh Sangat and partaking of kiran even if you do it silently also counts. When In Jail Bhai Sahib still fulfilled this most rewarding rehat and used his karha as a Vaja.
Kirtan turns Kaljug into AKalJug.