When performing a Zwift workout the size of the font for the plan i quite small. Especially if you, as I am, are short sighted. Note, riding with glasses does not really fix this problem, and you end up with sticky glasses.
An improvement would be if the size of the workout plan could be changed by the user, if the font of current and/or upcoming block would be bigger than the other blocks, and/or if a short description of the upcoming block would be presented (as is done at the end of some workouts to encourage zwifters to finish strong or try some other workout). Note that this last suggestion could be made in a way to allow users to turn on or off the description.