Be unselfish. That is the first and final commandment for those who would be useful and happy in their usefulness. If you think of yourself only, you cannot develop because you are choking the source of development, which is spiritual expansion through thought for others.
My brother was an improviser. He's now a lobbyist, but he used to perform improv in the city when he was in high school, and one of the funniest guys I know to this day.
So organic farming practices are something that, to me, are interlinked with the idea of using biodiesel.