Here are some website with physical activity plans for teens:
http://www.fromcouchto5k.com/
https://hundredpushups.com/
https://twohundredsquats.com/
https://twohundredsitups.com/
https://www.youtube.com/user/livestrongwoman
https://www.nhs.uk/live-well/exercise/
http://www.fromcouchto5k.com/
https://hundredpushups.com/
https://twohundredsquats.com/
https://twohundredsitups.com/
https://www.youtube.com/user/livestrongwoman
https://www.nhs.uk/live-well/exercise/
Some fitness trackers are listed below. It's best to give a few a try and see which one fits in best with your busy lifestyle.
https://www.loseit.com/
https://www.mapmyrun.com/
https://www.myfitnesspal.com/
www.entryworks.com/
https://www.loseit.com/
https://www.mapmyrun.com/
https://www.myfitnesspal.com/
www.entryworks.com/