There are certain bodyweight exercises that just deliver results, that are tried and true, and that take some effort to master. One of our favorites is the push-up. A classic exercise you probably learned in gym class as a kid. And as you probably know, push-ups are hard. They simultaneously work your shoulders, arms, pecs, back, and core.

For Estella Gong, push-ups were difficult from the get-go. But after working on her push-up form and increasing her push-up difficulty, Gong was able to accomplish quite a lot in 100 days. Check out her inspiring video below. Can you do a clap push-up?