Worshipping ought to be a personal experience. At the philosophical level, the object of worship is worship itself. Nothing is sought as the end result. However, in order to reach that advanced level, we need to begin and practice praying systematically so that our faith in the Supreme Being is gradually strengthened.
Faith is the critical element without which any ritual or religious practice is meaningless.
And, further, it is of no value either here or hereafter. We cannot sufficiently emphasize the powerful suggestion that is so easily and so often ignored. Krishna's warning is that we should never engage in a puja ceremony or any other ritual if our heart and mind are not singularly devoted to it. The best reason is the most direct and simple reason and that is to surrender to God to seek His protection and pray for inner peace from the eternal conflicts that afflict humanity. Let us simply resolve to pray to Him to grant us the wisdom to have faith in Him and with that faith seek His infinite grace so that we can live a dhaarmic life full of joy and freedom as we serve Him and the society at large.