My biggest problem with workouts was the continuous concentration on counting the repetitions of movements and remembering the next movement in the complete workout program. I also did not like follow any trainer or instructor because there speed was sometimes faster sometimes slower as I wanted. So I decided to create my own method of training and created an Android App. With this Android App, I can focus on the workout and the App will do all the annoying tasks. Now I am able to set up my own workout program or load the program of any trainer, change the speed according to my taste. I can use a built in timer or a Bluetooth button to control the application. It counts for me the exercises and tells me when I finished with one exercise reps and can start a new series of movements.
Gym exercise assistance (GymEx) helps you focus on your workout and you do not need to count repetitions or you do not have to remember which exercises will come next. It can be controlled with Bluetooth button. This application is free to use. After 1000 movement it will offer the pro version, but it remains usable.
Instructions: https://www.instructables.com/id/DIY-Workout-Player-and-Editor/