When the headache sets in, when your throat is dried out and when you start to feel so frail that you can’t even move a finger, remember all of the forgiveness and reward that awaits you.
It was proven in the Sahīhayn from the hadīth of Abū Hurayrah that the Prophet (ﷺ) said:
“Whoever fasts Ramadān out of faith and in the hope of reward, his previous sins will be forgiven.”