Once your body adapts to the stress you put on it, it's time to change the stress. Personally, I'd only run for a long distance if I were being chased by a hungry lion, so it's unlikely you'd catch me on the treadmill. I prefer to do weight training circuits combined with calisthenics, sprints, and jumps to keep things interesting. You can mix things however you wish, as long as you find it challenging.
This may explain why the fat-burning effects of eating more protein were confirmed in a study published in the American Journal of Physiology. One group was fed a high-protein diet (just over 1 gram per pound of body weight per day) while the second group consumed an amount closer to the lower recommendation of the RDA (recommended dietary allowance). The group eating the higher-protein diet burned the most fat.