When you are feeling sick, always remind yourself everything's happened for a reason. Always remind yourself maybe Allah wants to test you because of your past sins. Always remind yourself that Allah is always loving you, so that He gives you this test and you will always remember Him.
He will never tests His servants if He knows we can't overcome it. So if He tests you, He believes you can overcome it. Stay strong because of Him. He believes you, so you have to believe Him no matter what.
And remind yourself that Allah is always opens His doors for His servants to repent. Always open. Remind yourself okay?
Everytime in Dua, don't ever forget to ask Him to give you a good health so you can be able to do all the good deeds, and all the things that He loves. Inshaallah amin ya rabb.