Give up the "but." You know, the "I want to go out, BUT I can't cuz I have Crohn's". Don't get me wrong, there will be days that you just "can't" because of your illness. There's a difference. You have to just do it sometimes. Even if you're feeling a little bit "fine", take that opportunity.
Accept reality. You have an incurable, chronic disease. Until there is a cure, you need to live with it and do what you can do make it livable. It took me years before I accepted the reality that there wasn't much I could do about it. I could watch what I ate and could "control", sometimes, the symptoms, but not all the time. When the flare comes, it comes and when it does, deal with it the best you can. If curling up in a ball is it, then do it. When the symptoms pass, you get up, brush yourself off and continue on. If not, it will smother you, take control and consume you.
Like the song by Chumbawamba - Tubthumping
But I get up again
You're never gonna keep me down