This is me, except I would substitute "week" with "ride."

I think it kinda has to do with the type of personality I have. I pace back and forth when I think. I naturally walk and talk fast. I'm constantly moving. I'm the guy who sits behind you in the lecture clicking his pen. I'm just kinda naturally high-strung.

Its not til I get to my destination (out of breath, of course) that I ask myself, "Why the hell did just sprint to the grocery store?"

I just have a terrible time pacing myself.
That's why I prefer riding with friends, that way they set a pace that's more comfortable and sustainable.

Of course the obvious solution is "HTFU"....but w/e.....