First thing first. Its Usha 'Paan' and not Usha 'Paana' as people mostly pronounce it. The Hindi word for it is 'उषा पान चिकित्सा' , and as you can see it's 'Paan' and not 'paana'. English has a made 'arjuna' of 'arjun', and it looks like, it has done the same with usha 'paana' as well ! Anyways ...
'Usha Paana Chikitsa' as daddu said, is made up of three words. Usha - meaning dawn or subah, Paan - meaning to drink or consume (here it means water and not wine lol !) and Chikitsa means therapy. So thus, 'Usha Paan Chikitsa' means treatment though water. As word usha suggests, its meant to be taken at early morning. Daddu used to wake up at 4 O Clock, lol ! Not ever own can do that ! But the chikitsa is meant for a particular time in the early morning , preferably before sunset.
Its may look as simple as drinking water, but looking at the way Daddu lived all his life, fit and fine, and almost for a century., I can vouch that this simple looking water therapy works wonders to your health, not only keeping you physically helathy, but aslo mental cheerful and positive through out your life !