OK maybe I'm one of those who "seem" to have it all together outside of therapy. But really, I think for myself anyway, it's forcing myself to do things even when I don't feel like it. Forcing myself to go out with friends, to clean the house, to keep my job going and to try to have some fun in life. I think it's hard yes, but the more I force myself to do something the easier it becomes. And I know I won't do it naturally so I do have to make myself do things. Strange but true. I could truly isolate myself all day because that in all honesty is what I really want to do. Hide from the world just like you. But I know that would not get me anywhere.
I think you have to start small, with something you think you might enjoy doing. And then just do it! There is no magic answer, unfortunately.