Your team deserves it.
People have joined your team because they believe in you and/or they believe in your mission. Hopefully it is both. They could be doing something else with another team, but they chose to work with you and that makes all the difference. Be the best you can be for them.
Your donors need it.
The people who pay you to do what you do expect a return on their investment. They have but their money where your mouth is (to twist a phrase). If you do not deliver in helping them meet their needs, they to will go somewhere else.
The times demand it.
The needs are great and the world is looking for great leaders to do great things for the greater good. Why not be one of them?
It is worth it.
There is no greater reward than doing something that matters, and doing it well. It is also great when someone notices, but even if they don't notice, you will. So be a great leader for yourself. This is one place where a good self image is critical. When your self image is poor and you work really hard on something, it is critical that someone recognizes your hard work and tells you. But when your self image is positive and you work really hard you can pat yourself on the back.
If you do not lead well your team or your supporters could just leave. There is something that is far worse. They could stay and make your life miserable. Stay or go, you need to be the best you can be.
What do you want to do with the rest of your life? You cannot change anything that happened a second ago, but you can do something about the next second, the next minutes, the next hour, the next day, the next year. You decide, and then do it!