People are confused.
Most Christians don't believe in God because they "need" him (well, they need him in the sense for salvation) but, people can get through life happily without him.
You will hear Preachers say otherwise, but, really, you need God to fulfill the purpose you were born to fill - living for Him (God).
If you are living for God or are a Christian for YOURSELF, to repeat a phrase, "you're doing it wrong"......
Your purpose in life is to "live for God"?
A Christian's life is supposed to be to live for God. Yes.
You are to die to self. It's all over the Bible.
You should take care of yourself, as, your body is - as a Christian - a "temple" for the Holy Spirit, but in all you say and do, it should be to the glory of God, all credit to him. If you have to be in pain or unhappy for His glory - so be it - His will comes before your WANTS and sometimes needs.