I've set myself an exercise target each day Chow - sometimes I don't make that target, sometimes I go over it, if I'm feeling good.
Its good to be kind to myself and to listen to my body. I wouldn't waste time feeling guilty - sounds like it was a rough day.
I reckon maybe your workmates did store up a few complaints but maybe that did that cos they know you're a good manager and you'll listen to them and get things done?
D