So much of what our bodies can and can’t do is all in our heads, if we don’t believe we can do it, we aren’t going to be able to. As soon as beating the 4 minute barrier became something achievable, people started achieving it. What was once considered impossible is now the standard for high level racers.
Can you get that one last rep in? or hold that plank another 30 seconds? Probably, but you got to refuse to not be able to.