I very much dislike the "sick or disabled people overcoming barriers and being happier because of what they have overcome" cliche. Partially because it seems to include the idea I should be grateful for my chronic pain. And sometimes, I just want to be cranky and admit that my health problems really suck. That being said... there are things I am grateful for that come from my health.
My health is helping me learn what's truly important. Because when you are worried about whether you end up in the ER, whether you will be able to make it out of the room that day, whether you will be able to hold down a job once you get out of college, etc -- then the things so many college students seem to be worry about just seem unimportant. Life is put more in perspective. I'm not saying I'm perfect or that I don't get upset about little things, but I don't care so much about people's judgments. Think what you want about my outfit or my spaciness -- I'm working hard just to be here and I have more important things to worry about. Through my health, I have learned a lot about what is truly important to me, what I want to prioritize in my life, and who I want to be for myself and my friends.
I'm not saying my health gave these things to me. I worked hard for them. I cried for them, ended up in the ER for them, laughed for them. My friends worked hard with me for them. I am still working hard to learn how to cope with my health and be happy and be a good person and a good friend. And I still have a long ways to go. But my health gave me a vehicle to learn, and for that I am thankful. I have never been happier or more proud of who I am--and part of that is what I have learned with my health.