Well I'm not so young, I'm in my 50s - been playing for 35 years, though played very litle between age 35 and 48.
It's not like I've ever been much good either, so I don't have old skills to fall back on, though I did play with my mates once or twice a month for about 10 years (bass more than 6 string)

Anyway I have been playing (6 string) an hour or two every night for the last year or so, and at last am making good headway.
I usually do exercises for 5 minutes.
But I still notice it takes around half an hour to relax, be able to listen to what I'm doing, and get the hands doing what I want them to do.
Feels somehow like getting in the zone - whatever that is.

Is this just down to age or normal?
Any tricks to shorten that warm up period?