I'm in a similar situation to the OP, I'm almost 55 and the rest of the band are in their late 20's early 30's There are differences musical taste wise but nothing ageist. I'm old, fat and have no hair and I take the piss out of myself on the those 3 things because there are people in this world who are dying from something horrible, starving....... so (for me), being worried how I look etc is not an issue as I've put it prospective.
In this age there is more emphasis and what you look like and your age rather than who you are and what you can do, it sucks big time but that's the world we now all live in.
There is lots of good advice in this thread but as a few have stated before, BE YOURSELF