Managing your time in college is more complicated than setting a schedule. Among other things, it's also important to regularly ask yourself, "Am I involved in activities that are important to me, or do I participate in them because it's important to someone else?"
It's not uncommon to join a campus club or group as a favor to a friend or because you've read that membership will look good on your future applications. But, if you're not feeling it, it's better to move on.
To help keep your priorities in check without becoming overextended, cut low-value activities at the end of each semester and only continue with ones that you highly value.
Your time in college is limited—and the spare time you have for extra-curricular activities is even more so. Choose activities that are meaningful to you--even if it feels like an awkward conversation when you quit.