Isn't she gorgeous! What's 22 in human terms? I've known horses who made it into their mid-30s.
I've heard various equivalence systems, but you would probably consider her about sixty. She has some of the signs of age - long teeth, loose lower lip, hollows over the eyes - but she's ridden every day and is in excellent condition with plenty of muscle. She has a bit of an advantage because she was never broke to saddle as a broodmare so she hasn't got the wear and tear on her frame that a horse in continual use would have -- she was 14 before she had a rider on her back (me). It was no big deal - she did turn around and give me a quizzical look, like "What are you doing up there?" but she's an essentially cheerful horse who's very human-oriented (from all those years in the breeding shed) so she quickly became a very good riding horse.