Strength is all about technique, control, and state of mind. Did anyone ever watch that show on the discovery channel last year with that thin girl out-lifting all the huge body-building guys. Or an average looking old guy being able to bend wrenches in half or tear through phonebooks because he understands how to leverage the muscles he does have in highly-effective ways.
I think there is still a common misconception that the size of your muscles relates directly to how strong you are.
My own personal experience on the topic: I have this pull-up bar here. When I was young, I used to work out regularly, and I'd hang from this bar now and again and try to pull myself up. I struggled a lot with it, squirming and trying to pull myself up, I couldn't do it. I tried every day, and one day I managed to pull myself all the way up. That was a big triumph for me. Cut to recent years, I don't work out and am as scrawny as ever. Meanwhile, if I have to, I can do hanging pull-ups like they're nothing. It doesn't even feel challenging, and yet I have no muscles on my arm (seriously, my upper arm is comparable in width to most people's wrists.) It's all sort of muscle memory technique... my arms just know how to achieve pulling me up. This always baffled my sister, who worked out in the gym a lot for sports, and had more muscle on her arms than me, yet struggled to pull herself up at all. Like most people, she thinks muscles = strength. To this day, she is still trying to figure out how I'm pulling up weight so easily without any muscle.
So yes, that's my little story. And it applies to every form of muscular activity, weight-lifting, running, jumping (haha, I've known so many people who can't jump at all), punching, kicking, whatever.
It's not the size, it's how well you use them.
