In broad terms I think happiness is a choice. There are lots of people that seemingly have everything good you could want- financial security, good health, strong relationships, etc.- that are miserable. And there are dirt poor folks, people with terrible illnesses, etc. that are always pretty happy. A lot if your personality and general disposition but IMO life is about 30% what happens to you and 70% how you deal with it.
That said in the first weeks of sobriety all bets are off! It's a huge adjustment, physically and emotionally, and it doesn't occur overnight. Do a search for PAWS and you'll see it's a process. It takes the body awhile to "right the ship" after years of chemical abuse. But once you begin to recover physically you can begin to work on the rest.
For many/most of us the period of adjustment can be a year or so. In that first year there are lots of good days and few bad ones, but life is a bit more of a "challenge" at first.