If he's doing push ups and trying to crawl, I would just leave him to it, let him get some practice in, and only go in to shush pat once he is really crying for you.
At this age, lots of parents have to switch to pick up put down. What that means in practice is that you wait until he is really crying, then try to settle him in his crib for a minute or two, then pick him up for just a quick reassuring cuddle (no more than 30 seconds really), then lay him back down and continue to try to settle him in his crib.
Both of mine were tummy sleepers at this stage, I used to put a hand on their butt and firmly jiggle from side to side, seemed to work better than a shush-pat to settle them. Whatever method you're using, remember to only do it until they are calm, not asleep. Once they're calm, take a step away from the crib. You want to be out of the room before they fall asleep.