Just hit my 40th birthday recently and I really felt "it"
Body's taking longer to recover
Mind's getting less sharp at times
I wont say that it is old, but more care is required if one wish to lead an eventful and active life at this age.
I seen many around me succumb to what's commonly known as "getting older" but it is a phenomenon usually associated with people who were less self-disciplined to begin with.
Of couurse, maintaining the body is easier with pure hard work and good diet, but the mind is the key thing that is inevitably harder. After all, a person at 40 by all common knowledge picks up new skill and digest info slower than younger person in general.
My solution is to forget some non-critical info, things that I can rely on others to recall, or perform and focus more on key "skills" I need to pick up. It is something like the Pokemon game where each Pokemon has 4 skills max, and you got to delete one old skill if you wish to add a new skill.
Life has been very good this year for me, by my own standards.
I hope for more good years ahead for my circle and the kitties.
Will update again as usual near end of the year.