Milestone pod is a small, cheap device that can track the efficiency of your runs. It does not a need charger and basically, you don’t have to care about it at all. The pod will detect your movements and track your activity.
A smart scale could be a very simple way to weigh yourself. It’s the end of notes, papers and other manual methods. You can just stand on the scale and all your results will be saved automatically. Smart Body Analyzer by Withings offers you this and some other interesting features.