So my guy suffered a check ligament strain back in December. He's been on stall rest/hand walking and walking undersaddle for the past few months.
He's now sound and cleared to get back in shape so I've been trotting him for about 5 minutes/ride with lots of walking before and after. He's pretty lazy and just kind of slugs along at the trot. I'm afraid of reinjury so I don't want to push him, but I don't want to underwork him and not get him strong.
Should I just let him jog at his own pace for awhile or should I make him actually trot? I'm also worried because he sits on his forehand when he goes slow and I don't want added stress to his LF where the injury is.
When I bring a horse back into work after an injury I ask them to work properly to the best of their ability because they are less likely to take funny steps that might strain the injury site. I pay very careful attention to the individual horse's "I'm getting tired" signals, and as soon as those appear I ask for a little bit more (like half a 20m circle little bit) of correct work, supporting them as much as I can and then quit.
In your case I'd be even more insistent that he work properly because it would take strain off his injury site.
I watch the clock very closely when I'm rehabbing so I can be sure not to do too much when the horse is feeling good, and also catch it quickly if the horse is struggling and needs to quit early that day. It also allows me to go by the "increase effort OR time, but not both at the same time" idea more easily. In most cases I added walk time once a week, and converted walk time to trot time (or later on trot time to canter time) once a week three or four days after the increased walk time.