103kgs, started walking and have rashes in groin.

it is damn difficult to build habits, i am so exhausted and on verge of tears over what i have done with my life. i ate till i became 103kgs. now on a phase to change, i feel stuck. i was walking today and ended up with a bad rash between my legs. any tips what to do for this? and for bad days where i dont feel like doing any excercise?