Not sure if I can, but I'll try. (Careful not to use this with people who don't get that your time is your time.)
Let's see what I can do.
Why? Because if you've already gotten your priorities in a row, and you're getting everything done, but you're not doing anything new, you're actually doing something really naughty: You're missing opportunities.
Opportunities to learn. Opportunities to make friends or contacts. Opportunities to strengthen your ties with people. Worst of all, opportunities to further your dreams.
How can saying no influence your dreams? Well easy. If you randomly get approached to try something that you've never done. Something you're hoping to do one day, but are terrified to do now, because of your lack of experience. What do you do?
I would say two things: 1) That I'm not experienced and therefore can't make promises. BUT 2) that I'd LOVE to try it anyway if the person is willing to give me the chance.
Because I can actually get way ahead of the game compared to if I say no. And even if I don't do as well as I could have had I did the same thing later, at least I got to learn. AND the person I did it for now has a relationship with me, so one day, if I really am ready to take on the thing I want to do, I can contact him/her again.
Sometimes, seemingly unrelated favors can lead to something important to you later.
I'm not saying that one should say yes to everything that everyone tosses your way. But don't just say no. Think. You don't know if something might lead to the opportunity of a lifetime. So use your yesses and no's wisely.
Have you ever said yes to something that led to a great opportunity later?