New workout program

Yesterday I started walking for an hour over lunch with a coworker. We are averaging 3.5 miles per hour. I also started doing some circuit training with my brother after work. We do another 3.5 miles in an hour plus some body weight exercises.  My arms and legs are sore but in a good way.  Two days in and I have already walked more in 24 hour period than I did in the previous month!  I just need to stick with it.