My best guess is that you're not moving fast enough to get active minutes (which I know is very unhelpful if you have limitations that make walking quickly challenging or impossible). My active minutes tend to only accumulate when I am doing 100 steps or more per minute, not any time I am continually in motion. If you did 13,000 steps in 4 hours, that averages out to 812.5 steps per 15 minute period. At about 6 miles for a four hour walk, you are walking at a speed of about 1.5 miles per hour. I usually see active minutes appear during 15 minute stretches when I hit or exceed 0.8 miles, which is more like 3.2 miles per hour. The math that Fitbit uses to calculate the data that is presented in your dashboard tends to be pretty opaque, but they recently switched from awarding "very active minutes" to awarding "active minutes," which should, accoring to their help article, *increase* active minutes earned and result in "a higher active minutes total than you previously saw." So the numbers I talk about above may explain Tonyworthy's issue, but not JosephR's, unless you've recently slowed down, Joseph.
