There are many documented incidents of seemingly frail people who have exhibited inhuman strength in the face of a dire situation.
Heroic acts such as someone lifting a car off of someone to save his life, are well-known and not as rare as you may think.
Believe that you are strong and powerful.
Train your mind not to accept weakness or limitations. And then, train to ensure that you are as prepared as possible to respond to whatever life may send your way.
Ban the word "can't" from your vocabulary.
You must train your mind and spirit, as well as your body. Napoleon Hill stated,
“Whatever the mind can conceive and believe, it can achieve.”
Never give up and never give in.