I reckon it is old age to an extent. I am getting it too at almost 30 years old. Now I haven’t been riding enduro bikes all that long but have raced downhill MTB and a few other similar sports that require some ‘commitment’ at times. I can say that I used to have a bad stack, get up, get on with it (if nothing was broken) and not think about it. Adrenalin did it’s job and I was straight back into it, no looking back.
These days I have noticed that I do get shaken up by these crashes and need to recoup for a period of time to find my ‘mojo’ again. This only normally takes a few minutes as the adrenalin seems to overtake my fear and I settle back in.
The point is that is does take me longer to find my groove again as I get older. You also have a better appreciation of what it feels like to crash from painful experience and this bears down on you too. Almost everybody is more sensible when they get older than when they were young.
I agree with the advice above though, clearing your mind and trying to focus on the task at hand is the best way forward. Bike fitness and weekly rides will certainly help too.
If I can ride with a bunch of 20 year old guns from week to week on a fiesty 250 crosser in 14 years time I will be very happy 