hmm...are there any exercise guru's on my flist?

Say you're a very fat man who is attempting to exercise. Unfortunately, the only exercise you know how to do is walking on a treadmill. Let's also say that you have weak knees and need to build up the strength in them.

What do I do?

I gotta lose 150 pounds by next summer.

Just please, don't say the words elliptical and machine in the same sentence.