Start from fitness, not from age
Chronological age tells you surprisingly little. A twenty-two-year-old who has been ridden steadily for years is a working athlete with an old birth date; a seventeen-year-old who has stood in a field for three seasons is an unfit horse who happens to be younger. If your senior is already in regular work and sound, there is rarely a reason to cut him back simply because a birthday passed. If he is returning from a break, rebuild him as you would any unfit horse — walking first, adding short trots on straight lines, and weeks rather than days before canter or hill work.
Shape the session for older joints and lungs
Warm him up longer than you did at twelve: ten to fifteen minutes of purposeful walking before trot work gives stiff joints time to loosen and old airways time to clear. Choose ground with give in it — neither deep holding mud nor baked, jarring tracks — and treat steep descents and tight turns as the expensive part of the ride, because downhill work loads forelegs and hocks hardest. Keep sessions varied but unhurried, end while he still feels willing, and let him cool fully; an older horse's temperature regulation is slower in both directions.
Recovery is the honest scoreboard
The session itself can flatter him — many seniors are cheerful and forward while out, then pay for it overnight. Read the report the next morning: does he walk out of the stable level and keen, or short-striding and stiff? Is he lying down and getting up normally, eating up, and moving freely round the field? A horse who is bright the next day has told you the dose was right. Two dull or stiff mornings after similar rides mean the work, the ground or the distance needs cutting, whatever his enthusiasm under saddle suggests.
Rest days do half the work
An older horse builds and holds fitness more slowly, and loses it faster, than he did at ten — and he repairs more slowly too. Alternate working days with rest days rather than riding in blocks, and let rest mean rest at liberty: turnout where he can wander and roll, not a day standing in. Light in-hand walks on off days suit a stiff horse well, keeping joints moving without a rider's weight. If his schedule includes a longer or harder ride, earn it with the quiet days on either side; with seniors, the calendar matters almost as much as the session.
Work that usually needs to shrink first
Jumping, fast work, long distances and competitive schooling are normally the first things to retire, not riding itself — concussion and maximal effort are what aging tendons, joints and hearts tolerate worst. Many seniors thrive for years on hacking, gentle schooling and the odd pleasure ride. Have your vet look promptly if he develops a persistent cough at work, starts tripping, loses condition despite good feeding, or goes suddenly unwilling: those are not age to be ridden through. And because seniors are often shared between riders, grooms and loaners, KinsLe Care Teams keeps his exercise consistent — each ride assigned, its completion timestamped, so nobody guesses whether he worked yesterday or accidentally rides him twice.