Help Crawling

Has anyone got any tips to help my baby crawl, please? He’s just turned 8 months and has been army crawling since he was 5.5 months. He doesn’t even push up on his hands, he’s always on his forearms, and only gets on his knees if he wants to roll. I know some babies army crawl until they walk, and usually I wouldn’t mind, but he can only army crawl a small distance before he gets tired and gives up, which makes him upset. I know he wants to explore more but he can’t. Has anyone got any tips on how to make him crawl traditionally?