Standing all the time isn't healthy either, but one thing standing desks promote better is taking breaks more often. I'm more willing to walk around and stretch

Standing all the time isn't healthy either, but one thing standing desks promote better is taking breaks more often. I'm more willing to walk around and stretch if I'm already standing, than if I'm sitting. I've been using a GeekDesk for 2 years now. I recently purchased a LifeSpan Treadmill (just the base) for my standing desk as the next step, and really like it. Careful though, you can't go from sitting to treadmill, it's too much body shock, you'll need to ease into standing for a few months first.