I think the key is in my illness of schizophrenia being the 'thorn in my flesh', where I must begin to embrace this type of suffering. In 22 years, I have gotten bipolar, schizophrenia, sexual addiction and a bad case of diabetes. I think if I weren't a Christian I've had given up by now.
I haven't fully accepted the suffering of the illness yet. The common symptom of schizophrenia is that you don't believe what is real, you instead believe false beliefs. Delusions are very common with people dealing with schizophrenia. And this is true when you are trying to believe what is real. So no wonder I struggle. Try, pretend, to believe that there is an illness which affects your thought life. It can't be rebuked, it's not a demon possession or anything.. it's simply a case where communication isn't supported well throughout the brain. That's what I have. Look up this disorder on the web, the symptoms. You'll see these there.
So, since this is a suffering different than my diabetes, which I know how to control and what the heck is going on, I have been thrown to the ground in understanding anything worthwhile about this. My reliance is 100% on God. And he won't take it away. I've asked more times than Paul did. Now is the time I must rejoice in my weaknesses. But more importantly, God's hand rests on me, and I am realizing that truth. I must change my notion of what kind of awesomeness grace holds for me.
Please, anyone who feels led to, pray for those affected by schizophrenia and who don't know the Lord yet. It's the grand mal of all mental illnesses. But I'm starting to believe, by faith, that I will not be lost but I will believe where I am - inscribed in the palm of God's hand.