Famous American Ninja Warriors Kacy Catanzaro and Brent Steffenson (first 3 are them) love to use bodyweight exercises for training.

---

V-Up Crunches

Jog in Place

Toe-Touch Crunches

Jumping Lunges

The Gymnast

Plank-Ups

Candlesticks

Plank With Alternating Leg Lift

Scorpion Push-Up