This doesn't work for everybody and its a big decision, but sometimes having something that you have to take care of (such as a dog or a cat) helps you build consistent routines and develop a sense of responsibility outside of just yourself which can cross-pollinate into other areas of your life.

For example having dog means having to take it out regularly for walks and feed it regularly. And in the words of the immortal Calvin and Hobbes, they make for excellent fuzz therapy. Good luck and hope you start feeling better.