Atta boy!!!! :)
It's 100% fine and good for a person to receive disability benefits and to spend more time resting and focusing on other wellness factors if that's the best path available to them. These folks, too, are facing their days and claiming victory each day. But if you've determined that employment at a standard gig is the optimal path right now to your well-being then YES, WAY TO GO!!!!
Doctor ideas, including prognoses, are often erroneous. It's great that you know your ability and live it :)))))
I think you're brilliant for deciding to make it a half day, and for doing gentler things for the second half.
And if ever you decide that working a standard job for an out-of-home employer is not the right fit even en route to other plans, and that disability, etc, is, I'll heartily congratulate you on that move, too.
You're a strong, bold, proud person who knows himself, takes care of himself well, and shows up for life every day. Total badassity, yep!