I am 50 and have been in "originals" bands since the late 70's.
The last act I was in had me at 50, a frontman at 37, a
drummer at 40 and a lead guitar at 30 - who of course, we
called "the kid"
Since that broke up I have not found another thing that
likes "old farts" in my area
I used to do prog rock when it was the first time around
(Jon camp was may hero back in the day) - I applied
to several acts doing original prog in my area with pics
and samples - they liked me plenty - then when I mentioned
my age they stopped responding to emails....
Waaaay back in 1977, when I was 20, we had a drummer
who was 24 - I recall being weirded out by a guy who
was SO MUCH older playing with us!
Fortunately my mental retardation faded with age
Having the same musical goals and level of inclination
is all that matters (as others here have said so well).
Lately I play with a couple of acoustic guys just out
of proximity, but sure do miss "a band"....