How do you stay POSITIVE ALL the time but keep your EXPECTATIONS LOW? HELP!?

Its an Mental war its hard to b positive when in desperate and negative situtiations but it can b done I look at as y should I count myself out when everyone else is already doing that for me u know bein positive is always sayin to urself things can change for da better bcuz I say it can practice it I changes ur whole world u become more than ur situtiation.