My partner in the biochar stuff, the guy who does most of the inventing, a lot of the fabricating, and still has time for a side gig trying to help poor folks on the Mexico side of the border, is 80 - he works at least six 8+ hour days each week and is more productive that most people I know of any age. He lives in self administered poverty with basically only Social Security for income (we aren't making money yet). His strong life mission is climate change mitigation and the alleviation of poverty and suffering everywhere.

You never change things by fighting the existing reality.
To change something, build a new model that makes the old model obsolete.
R. Buckminster Fuller