Try this 11-minute core workout you can do at home, or repeat twice for a 22-minute ab circuit
Forearm plank: 30 seconds
High plank: 30 seconds
Side plank: 15 seconds
Side plank with crunch: 5 reps per side
Single arm/leg plank: 15 seconds
Rocking plank: 15 seconds
Knee-to-elbow plank: 5 reps per side
Standard crunch: 20 reps
Bicycle crunch: 30 seconds
Knee-to-elbow plank: 5 reps per side
Standard crunch: 20 reps
Bicycle crunch: 30 seconds
Source: wellandgood.com