Lifehacker: The Pros & Cons of Working While Working Out. Regular readers will know that I have a walking desk (i.e. treadmill with a plank to support my laptop) and I typically use it 4-5 days/week for 1-4 hours/day depending on motivation and pain levels. I set mine at 6% slope and 2.4 mph and I can do everything work-related except take conference calls (natch) or do finely-grained graphics work.