I'm pretty new to exercise and am currently doing a short HIIT workout 3-4 times a week and trying to walk more. I tried C25K but it hurt my knees, however, I've lost almost a stone in the last 6 weeks and am keen to have another go soon now I'm not so hefty. I'd love an activity tracker to count my steps and see my heart rate etc but the more I read up on them the more confused I am. Everything seems to point to them being frequently inaccurate and prone to breaking after a couple of years 
. I could spend up to about £100 on one but will I just be wasting my money?