1. A training device comprising: at least one sensor configured to measure at least one physical performance characteristic of a user during a workout; a first computing device that is portable and selectively attachable to the user, including: a receiver configured to electronically receive an electronic training script defining a sequence in which the user is instructed to perform a plurality of activities, and a presentation unit configured to prompt the user to perform a next activity of the plurality of activities in the sequence based on a measurement of the at least one physical performance characteristic indicating completion of a previous activity in the sequence.