How to Boost Stamina for Workout: Building stamina requires time and practice, and the payoffs are worth the efforts. Good stamina is key to getting the most out of your training sessions and enjoying your life. For instance, if you can’t carry on exercise more than 20-30 minutes, then you’re probably no advantage from the workout and may be actually wasting your time and energy. Therefore, if you want to boost your stamina with exercise here are some ways that can help.