Although I don't have a sixer (more like a four-er), I'm in very good shape.
I'm on my way to getting one though.
I can run, of course.
I can hit the heavybag just as long as everybody, with intensity.
Just about any workout that requires stamina, I'm ok.

But when it comes to jump ropes, damn...
The acidic acid builds under my arch, to the point where I HAVE to stop or I'll fall.
My heart rate is good, it's just this ODD occurance.
On of the trainers told me to stretch the ankles and the arch afterwards and it helps.
I hate when I have to stop roping early, because I'm so proud of my work ethic.

THAT is why I want to build time. I can almost do just about everything with consistency,
speed bag for rounds after rounds... but them damn ropes! haha

20 minutes huh, that's pretty good.
I think I may stick with Joe Frazier's advice in his book
and work my way up to 15 minutes and stay there.
No way in hell I'm going to do 30 minutes!
I'd rather run 2 miles for stamina and jump rope 15 minutes.