To consider working less now?

[Coffeebiz]

I'm 51, single, mortgage paid off a couple of years. I work 4 days a week, but am now seriously considering reducing to 3 - it's possible in the type of work I do. Some - but not all - days, between traveling to work and working, I'm gone 10-12 hours and it's taking more of a toll on me physically now.

AIBU to consider this?

Not at all. It sounds like a sensible approach. I'd just check 2 things:
Are you fully au fait with the affect on your pension.
We do get tired as we get older but is it definitely an age thing? Have you been to gp to check thyroid, menopause etc.

Sounds sensible to me.

I have a private pension, so I'd manage to keep the same payment into it.

I haven't had a recent checkup but plan to do so soon