Core Up!

My boot camp seems to be transitioning to focus on core and strength training more so than it use to.  I can clearly see that my weakness is core vs. something like strength training or cardio.  It use to be that I could do planks for days but for some reason as of late I find doing a plank for 25 seconds to be the hardest thing in the world. 

Today after our 10 min jog warm up we did an obstacle course with some circuit training.

Our first station had 4 maybe 5 stair step stacked and we had to jump using one leg from side to side. 
Moving on to the second station we did push ups with sit ups and mountain climbers using a core ball.
We next held a 30lbs ball while standing on a core ball and did 15 squats followed by 15 shoulder press.
After that we got on the tread mill with a incline of 5.0 and speed up to 5.0 for 60 sec.  (my speed was 4.2)
We did 3 sets of leg curls on the machines followed by triceps dips, lunges, and ended on bicep curls.

All exercises are done in 3 sets and upon an early completion he adds more exercise so that we can work out for 60 min (non stop) He is such a nice guy!