One of the toughest things to do is to learn which things to say no to -- and which to say yes to. It's tempting to want to do all the things. However, chances are that you say yes to more than you should.
When you are bogged down by obligations, you reach the point where you need to say no, for your own sanity. Unfortunately, when you try to hard to do all the things, you might end up in a situation where you can't say yes to the opportunities you really want.
In order to avoid becoming overcome by all you need to do, it's important to understand what really matters to you. Narrow it down. Focus on the essentials, and then expand from there, only saying yes to the things that you really want to do. And if you need help figuring out what's most important, create a life map.