Here are the 5 most effective exercises for your strongest and fittest core ever. A strong core not only helps give you defined abs, but it helps improve your posture and confidence! These moves will work your upper and lower abs, and obliques while focusing on mind-muscle connection and control. This is a great workout for all fitness levels because it’ll provide modifications as you continue to build up your strength and endurance. Oh boy, your abs will be popping after this routine!