I can't remember the age of your DS so it may be different but my DD is 10 and her strengths are in the comprehension, verbal areas so once we get her on board she "gets it" and cooperates.
I explained it using the analogy of a backed up bath tub. "Up until now we've been dumping out the water. Now we are working on clearing the clog."
We do 15-20 minutes every day that she doesn't go the the vision gym for an appointment. Some excercises are fun, or at least they were before the novelty wore off. Some are hard work that make her eyes hurt, or make her feel dizzy or give her a head rush. I report all of these reactions to the VT. Some show the excercises are doing their job but one response - I think it was seeing spots after an excercise - could potentially indicate an issue that will mean a re-eval and dilation by the DO sooner than expected.
4 weeks in and the excercises she has been doing longest are getting easier. One benefit - the reading teacher at school said the first day DD had her reading glasses she went from 59 wpm to 81. I take that to mean the diagnoses is accurate and the first intervention was extremely effective. They tell us they plan to fade out the glasses as her vision improves.
I think buy in is crucial for this to work. Last week when the VT was showing me what they had worked on I was absolutely stunned that DD had been able to do it. I mean STUNNED. It must have shown on my face because DD just looked at me and said "We have to do whatever it takes to clear that clog - right Mom?"