So I'm the last person to say that having sore muscles doesn't feel satisfying, but good workouts don't always HAVE to make you sore. Sore muscles just means your muscles were exposed to a stress greater than it's used to. Trying to make yourself sore all of the time reduces the ability for muscles to recover and can lead to strains and tears.
4. Double Crunch. Begin lying flat on your back with your legs stretched out in front of you and your arms by your side. As you crunch your abs, raise your chest, and tuck in your knees so that your upper body and lower body meet above your hips. Slowly return to starting position, making sure your shoulders and heels meet the ground at the same time. Repeat this 10 times, and complete three sets.