I can tell just by my mood when I have not been active enough physically. Winter time is one of the biggest problems for me, especially because I hate the cold Ohio weather. Because it is not summer, I don't have too much of a problem keeping active and moving around. At work I am almost always on my feet, and at home I make sure to play with my daughter and garden daily, even when I'm tired.
The Harvard School of Public Health offers quite a few reasons to get off of the couch and keep moving. For me, physical and mental activities are the biggest benefits that I could give myself. It is super easy to sit on the couch and read a book all day when it's 90 degrees out, and I can make all of the excuses in the world to not move. Those won't help me though.
I have discovered how much physical energy just house chores require, though! Line-drying clothes has a lot of bending and lifting, picking up baby toys has a lot of walking and bending, and even just carrying my daughter around while I vacuum helps a ton. Almost makes me want to clean the house! Well...sometimes.