I don't enjoy going out anymore

Me and some friends had arranged to go to a little festival tonight. I just bailed on them last minute. I feel awful, I should have listened to my gut and not agreed to go in the first place, but I was feeling optimistic when I agreed.

Just the thought of spending an hour on an overcrowded train, to arive at an overcrowded venue, to listen to shite music so loud I can't think, to get drunk and try to dance then feel awful the next day, and pay a ludicrous amount for the pleasure doesn't appeal to me at all.

I am 29, 30 in a few months. I've resigned myself to the fact I'm just old. A couple of years ago I would have loved something like this, but it's like a switch has flipped in me. I feel like I've been in a bit of a funk at the moment, so maybe it's a sign of depression, but I just find it so hard to let myself go and enjoy myself these days.

I think this is compounded by the fact I'm not where I want to be in my life. I would rather stay in and work towards my goals.

I'm not that tight with this friend group, but I can't help feel they hate me now, and don't suspect I'll be invited out much longer, which I guess suits me.

I guess this is a natural part of maturing, but I can't help but feel I've lost my zest for life. Can anyone else relate, or have any advice to deal with this?

Thanks guys.