Happy Birthday! Looks like I noticed this thread just in time.
I hope you had a good dinner with no drama. What you should do is buy yourself a present-- something you've wanted for a while, but wouldn't normally buy.
And when you think about making a mark on the world, don't forget to take into account the Butterfly Effect. You didn't just help those people you've encountered-- you've also set an example. Many of them will remember that and go on to help others. Your goodness and kindness will ripple out into the world and into the future immeasurably; you'll never know the extent of the good that you've done.
As for turning 50, it didn't bother me at all. Mostly because I don't really believe I'm that old. I don't feel any different than I did 25 years ago. I got a touch of gray and maybe some new laugh lines on my face (and I've definitely gained a bit of weight, but that just brought me up to normal). As far as I'm concerned, I'm going to live forever and there's no evidence to dispute that assumption.