Freeletics is the app that will get you in a better shape not only physically but mentally too. It will make you a plan for training depending on your availability, your space and your workout level. it will evaluate you after every one of your workouts, so you can set goals and most of all, achieve them.
PunchLab is a Mobile App that will turn your punching bag into a device able to detect, measure, and react to your strikes. No additional device other than your smartphone is needed. It uses the existing technology in your phone to give you real-time feedback on your bag workout and offers training routines pre-programmed by world-level athletes.
You can set reps of exercises in conjunction with intervals. Setting both will help you pace yourself during intervals and exercise at your desired level of intensity. A beep sound is played at each next rep. You just need to keep up with the beeps.
Runs in the background and notifies you of transitions in a workout with nice sounds.