Prince Charming history as told by his owner-

I "rescued" Prince 7 years ago from a 1,000 sq. ft. paddock that had nothing but red dirt. To my knowledge, he was not given hay or forage and had limited access to filthy sitting pond water.
Prince was given "a handful" of what looked like 10% maintenance grain.
He was 300 lbs. underweight according to my veterinarian and suffered from thrush, rain rot, white line disease, and various lacerations along his entire body. My veterinarian estimated him to be about 13 years old at that time. His current age of 20 has been confirmed by my current licensed equine dentist.
From what I could gather in the moment of seizing him from the current owners, he had been a barrel racing candidate for a 14 year old girl previous to their purchasing him, but had sat in their paddock for two years with minimal exercise.  According to his muscle mass he hadn't left that paddock in at least two years.

The entire first year of owning him (about 6 years ago) was dedicated to his rehabilitation. He was on a high fiber forage with an alfalfa hay mixture that he had access to 24/7, was out on pasture, and was fed a 15% grain with freshly ground flax seed and supplemented with beet pulp, vitamins, and electrolytes (of course he was gradually weaned onto all of this feed and forage). In one year he gained 350 lbs, increased flexibility, changed  in his personality, gained energy and motivation, and improved overall muscle tone and mass (body score from a 2 to a 6).

The next two years we barrel raced (lightly) in local rodeo circuits. He was exercised lightly (walk and trot sets with no barrels, including long warm ups and long cool downs, with maximum stretching time) 3 days a week and vigorously (walk, trot, canter sets, barrel patterns, flying lead changes, cardiovascular endurance exercises, with long warm ups and long cool downs and minimal stretching) 2 days a week. We barrel raced one weekend a month for about 2 years. During that time he had no soundness issues, was very balanced, and extremely healthy.

The following few years he sat in a pasture in North Carolina while I was in college. He was ridden twice a week at walk and trot to keep him moving. He was about 50-75 pounds over weight from an increase in pasture time and lush forage. Of course he was ridden moderately anytime I went home for break.

This past year he has been boarded in Lynchburg, Virginia. He has been a lesson horse for me when teaching beginner, advanced beginner, and intermediate western pleasure riders. He began having soundness issues in his left hock and gaskin after a major fall into a cattle guard where he suffered from soft tissue and muscle damage on the inside left hind gaskin. While the laceration has healed outwardly, he has never been 100% sound afterwards.

He has the hardest time when it rains. Anytime the barometric pressure changes he gets stiff and sore in his left hind leg. He often goes down to 50-75% weight bearing on that leg. Now that the cold winter has settled in his is also stiff in both hind legs. He flexes positive in both hind legs.

He is currently lunged at the walk and stretched daily. THAT IS HIS ONLY EXERCISE. He is too uncomfortable to trot for long periods of time without a rider. Occasionally he will canter or trot along with the herd but he cannot do so for more than 20-30 strides and he is extremely stiff the whole time. He is out on pasture 24/7 (blanketed and with a run-in) unless it is raining, sleeting, or snowing, or the wind chill and temperature drop below 32 degrees at which time he is then stalled overnight. But stalling him also makes him extremely stiff. The more he moves the better he feels.

He is currently supplemented with a Senior powder containing, Lactobacillus, Glucosamine Sulfate, Chondroitin Sulfate, MSM, Ester C (Ascorbic Acid), and Hyaluronic Acid (HA).

I spray his left hind leg with a mixture of essential oils each day
that promote blood circulation and prevent muscle soreness
or arthritic pain (this is simply to help him feel more comfortable)

He has been given bute on occasion for severe leg pain (maybe once or twice a year but not regularly).

He is currently healthy in the sense that he is a body score of 5, and has great teeth for a 20 year old horse. He has a good appetite, great hoof health, and exhibits generally normal equine behaviors and personality. Overall, he is doing "okay" with his muscle mass considering his inhibited movement.

In order to help his soundness and make him more comfortable consistently, I began supplementing Prince with InMotion.

The video here is of Prince before InMotion.