Wait up

I feel great...
And that's your first mistake!
If you're only as old as the person you're feeling
Then I better stop touching my -
Self, centred ways
Now seem to plague my days
I used to talk to cabbies, used to thank busdrivers
Used to say 'hey!' to train gaurds even pull all-nighters,
And..
I never thought about it much.
I guess you're finally losing touch.
I geuss I'm finally losing touch.
I guess you're finally losing touch
I used to tell the difference between.
15, 16 and 17.
And now they're all too young for me.