The above circuit is one that I plan to implement over the winter b/c I live in a state that gets tons of snow so my outdoor running will have to be put on hold until next April. To look at it on paper, it doesn't seem like much but halfway through the first circuit, you realize that body weight exercises are no laughing matter. My older son was winded after the first ten minutes...bless his heart for doing it with me.
And I recently did a front and side plank for 2 minutes after months of being stuck at thirty seconds. My abs were achy for three days..but in a good way.
I just wish my upper body matched my cardiovascular endurance, lol. I'm toned but not very muscular. I like to call my arms: 'Tori Spelling arms'.

I keep working at it but it's tough being an ectomorph, we don't gain muscle very easy. In the bodybuilding circles, they call us 'hardgainers'...now I know why. Oh well.