Ride him everyday if possible, feed him well, but don't overfeed, or all you'll get is a fat hyped-up horse. Wherever you buy your feed should be able to tell you what & how much to feed him based on his weight and how hard you work him.
I have 2 AQHA geldings, 10 & 15yr olds that I use for team roping. They stay turned out on 10 acres of grass with free choice quality grass hay, when I'm using them hard, roping & riding 4-7 times a week, I'll feed them each 1 gallon of steamed rolled oats in the morning & evening. When I don't use them hard I'll cut their feed in half, so they won't get to fat. This has worked well for me, they stay muscled-up and in great shape as long as I use them. Work into it slowly, a healthy horse can be rode and worked daily as long as don't abuse them. If he has the breeding, quality feed, and lots of use, he should turn out to be one well muscled horse.
teamroper2004