it is god who has created you weak then given you strength after your weakness and caused you to become weak and old after being strong. he creates whatever he wants. he is allknowing and allpowerful.
الله الذي خلقكم من ضعف ثم جعل من بعد ضعف قوة ثم جعل من بعد قوة ضعفا وشيبة يخلق ما يشاء وهو العليم القدير