Purport

In earlier Shloka Bhagvan Shri Krishna explained that those who perform any of the Yajna with dedication get free from the sin reactions of the actions and attain the state of ultimate purity.

In this case, Bhagvan Shri Krishna explained, that Yajna is not only beneficial to attain liberation but also for worldly people. In fact, without Yajna of any kind, nobody can attain success even in this mortal world. How then he can assume that he will be happy in the next world.

As we have read, Shloka#24 to Shloka#29 of this chapter explains different types of Yajna. They are Deva Yajna(worship and devotion of deities), Bramha Yajna( Complete devotion for God or enlightenment), Tap yajna(The renunciation, hard work, etc), Dravya Yajan(Charity), Yoga, Meditation, self-control and Janana Yajna(education and skills). To get success and hence happiness a person should be healthy to work and should have some skills. With working health and skill nobody can assume to get worldly success and happiness. To get at least workable health and skill of some kind one have to do either partially or fully of one or more of the above Yajnas.