Hmmm, not sure if you are using a med ball but it helps because it makes it fun! I just take my time with it, rest when I need and change how I throw the ball. After a while you go into BEAST mode and you just refuse to give up until you reach the number in your mind.
I was going mine in the gym but I no longer go to the gym that had the med balls so I need to buy my own real quick! I plan on using the med ball outside against a brick wall that is right next to the track I use and resume my abb routine after tempo. BTW, I just started doing sit ups and abs DURING tempo and I have noticed a change. Wow man, Charlie has his stuff down pack! You just got to put it all together and do it.