If you don’t like dumbbells, you can finally use another way to achieve the same goal. Training with a medicine ball is one of the most effective and the oldest forms of strength conditioning. You will need a 10-15 pound medicine ball and a few minutes of your time. 

In order to engage your obliques and abdominals, you can perform Lunge With Twist. This exercise is good for your legs as well, which make it a full body move. Step forward with the right leg into a lunge while you are holding a medicine ball in front of you. When you get to the lowest point (in your lunge) twist the ball to your right. This will rotate your torso. Return the ball to the center position and return to the starting position. Do 10 reps for each leg.
In order to perform Rolling Push-Up get into a high plank position. Place the ball under one hand. Then, lower your body in order to perform push-up. Press back up and move the ball to your other hand. Do from 5 to 10 reps for each hand.

Ball Fly exercise is a bit harder, so you will need some time to master it. Lie (face up) on a Swiss ball. Shoulders and neck must be on the ball’s center. Feet are flat on the floor and knees are bent. While your hips are raised, hold a medicine ball up. Transfer the ball to other hand and lower your arm down (it must be parallel with the floor). Then, bring the ball back to the center and move it to another hand. Do from 5 to 10 reps.