As most of us already know moving our bodies and getting some form of exercise is better than nothing. Basically Move it or Lose it.
My exercise of choice or what I personally prefer is doing Yoga. You do not need too much equipment basically a yoga mat for bare minimum and then if you need more props such as a strap, or blocks. All are not very expensive to get.
I recently went to our local half price book store and maybe I may have gone a little overboard but, I got 4 yoga DVDs for less than the price of a month long yoga pass/membership at one of our local yoga studios.
All of the DVDs offer something specific and give you a great workout in 20 min to 35 min. I can actually tell a difference in how I am feeling. I am sleeping better and not quite as stressed as I sometimes get.
If all else fails and you cant or do not want to do anything else grab a pair of walking shoes and go for a walk.