O.k. so this is a short one, and a bit of a digression. I found an online plan for the 5 minute plank, and I made it!
And these days I'm working on instituting the 4 minute workout in lots of versions ala Tom. The 4 min. workout is 20 seconds on/spring and 10 seconds rest/walking. Introduced to me as running, but Tom recently challenged me to do it with situps and pushups. I can do it alternating (situps and then pushups). Working my way toward doing the full 4 minutes with each. Need a challenge?