It took community to get you unhealthy. It will take a different kind of community to get you fit and well.
Motivation comes and goes; it's not a reliable source of fuel for lifestyle change. Instead, focus on follow-through: making a commitment and keeping it no matter what.
You're not lazy; you don't lack willpower; you aren't undisciplined. Changing habits is like learning to play an instrument: if you practice daily and fix your mistakes, you will achieve mastery.