I certainly have and do fail to engage. I kind of go in spurts. You could say my goal would be for the spurts to last longer and the gaps between to become shorter.
I think about this a lot when I “run” my 4-mile loop. It’s really more a combo of jogs with walking in between. By the end of the summer, I’ll be able to jog the whole thing without walking. Right now it might be 60% jogging. If I sprinted enough to become overwhelmed (with oxygen debt), I’d have to walk more.