@tfscythe first of all i recommend you If youre going to do something, dont tell people, dont post anything. telling others about your goals gives ur brain a premature sense of completion, reducing your ability to perform and execute. (studies: Gollwitzer, P. M., Sheeran, P., Michalski, V., & Seifert, A. E. (2009). "When Intentions Go Public: Does Social Reality Widen the Intention–Behavior Gap?").
finally, you should exercise for obvious reasons, so i will recommend you to just walk a lot, even if ur the fattest guy, because we are literally built for walking. low impact in your stress and body, etc.