Question
Is it permissible for me to intend to fast at night and say: If I get tired, I will break my fast; because I have stomach issues that tire me a lot?
Answer
I say, and with God's success: Your intention to fast is correct, and the fast is valid as long as you do not break it. Your statement: If I get tired, I will break my fast does not affect it, and there is no need for it. God knows best.