Noemi, you’ve discovered the same thing I learned: there is absolutely no connection between physical health and emotional health. We THINK there’s a connection because we LEARNED this. We were taught that our happiness should depend on how we feel. You’ve probably known people with serious long-term medical conditions who exude joy, and you wonder, "How do they do it?" The answer is, they have learned this lesson.
There is no essential connection between our physical circumstances and our attitude. We can choose.