1. Upgrade : Every time you upgrade to a level in the game, you can gain physical fitness.
2. Complete daily tasks : In daily tasks we can get physical props.
3. Use props : You can also gain physical fitness by using props. For example, you can quickly gain physical fitness by using 25 Flowers of Time to re-sign.
4. Friends give each other : We can obtain physical fitness through friends giving each other.
5. School exercise : You can also gain physical fitness by exercising in school.
The above is the detailed strategy for obtaining physical strength in the game "Outside the World", and I hope it can be helpful to you.