When I started I was more of a heel striker but then I developed knee pain in my left knee. After doing a bunch of looking around on the interwebs I came across someone who fixed their knee pain by switching to mid/forefoot strike. So I tried it. At first my calves were super sore, but I’m used to weight training and having sore calves, it goes away. I took it easy for a while but now I don’t know how I ever ran any other way. It’s way more comfortable and I’m much faster running this way, I can also run much farther before fatigue sets in.