There are three types of strengths: physical strength, mental strength, and resistance strength.
Physical strength is your muscles that you can increase by properly exercising and doing proper workout. When you do these two properly it helped boost your lifting strength to lift something up and handle pain from others in a fight.
Mental strength is when if someone mess with you you get offended which show that you're weak and if someone be mean to you and you overreacted it makes you seems weak.
Resistance strength determines your power to resist temptation. Your resistance strength can increase by doing things to make you strong like listening to songs or singing. But, if you do things to make you weak then you will give in to temptation.