A very simple thing I would do was to play a continuous motion exercise a set number of times, with a break in between. However, I stayed away from playing faster tempos and focused more on slower, more deliberate tempos, as slow as 20bpms even. Here's why.
I'll be uploading my methods for gaining and improving hand endurance. This first video is a basic description of my thought process going into the series as well as some recommended tools to use while watching this course.