Choose to be happy? I imagine that's a question people must answer for themselves.
When I was drinking, some things could make me happy but it tended to occur in passing and was usually coincidental. Mostly, I was tethered to a place in which I just existed. (And happiness as a state is the subject of some debate -- peacefulness, some say, is a more achievable place.) Whatever the case may be, alcoholism meant I regularly drenched my brain in a depressant, making ongoing happiness and/or peace beyond my reach, outside of my choices.
What I could choose -- and did -- was freedom from drinking. Consequently, I am both happier and more at peace.