There are plenty of things I have done and haven't done and they all (more or less) have resided on one specific thing: my decision. What happens with me is decided by none other. Traveling, laughing, drinking too much coffee, writing a book, singing on stage in front of strangers, dating, not dating, not being happy, being too happy, and a whole laundry list of items are decided by me and me alone. Honestly, it feels good to know it. That life - my life - is in my hands (more or less).
The same goes for you. If you are unhappy, make a decision (or perhaps you already have). If you want to get in shape, what's holding you back? Nothing. The only thing in life that keeps us from doing things or keeps us doing things is ourselves.
No one is going to make you happy. You make your own happiness. Sorry, pals, but that's just how it is. You make your own accomplishments. You make your own way.
All of this is written with "more or less" in mind. There is death, disease, finances, and perhaps prison (if you happen to be so unlucky), but from there, really, it comes down to you.
I would request that you make a decision with your life to be happy. To truly be happy. But if you didn't pick up on the fact that is what I was leading toward, then there is no point in me even making the suggestion.