There has never been another person like you on the planet...ever. And, there won't ever be another person like you again...ever. Inherently then, everything you do is unique. So why do we fill our lives like a Thanksgiving plate? Yes, we have many responsibilities that all need looking after. What we're talking about is YOUR unique contribution to this world.
If your "plate" is and inch deep and a mile wide (like your Thanksgiving plate) it's hard to know where your focus should go. You're not sure where to start every day. You can't do everything all at once so you go where you're pulled. When you do everything for other people you're abandoning your true self. This is ignoring the vital contributions you can have in the world.
When you give yourself permission to go an inch wide and a mile deep with the thing you "can't not do", you've signed up for huge contributions. Great, where do I start? You are great at a few things. Figure out the convergence of your gifts & curiosities. This is your sweet spot for making a difference. This way, you haven't bitten off more than you can chew, you can savor every bite!
PS Notice, we're not talking about "legacy". That's between you and your ego. It's the difference between "How do I want to be remembered?" and "Do I want to be remembered at all?". This is a whole other topic for another post!