This is partly why YC (and others) suggest being 2-3 cofounders in startups (the same idea should hold in hobbies as well): the social pressure to perform 'your

This is partly why YC (and others) suggest being 2-3 cofounders in startups (the same idea should hold in hobbies as well): the social pressure to perform 'your end of the bargain' is enormous and can do wonders for motivation / productivity.