When it comes to fitness, the math is quite simple: even a short workout is better than no workout. The perfect amount depends on your goals and your current physical fitness. Some beginners can only hold out about 10 minutes on an elliptical machine. Others keep on going for a full hour without breaking a sweat. In general, spending 30 minutes a few times a week working out is enough for an average adult. Of course, the intensity of your workout plays a big role too. You should adjust your workout to be challenging, but never difficult or painful. As a general guideline, doctors recommend a combined 150 minutes of physical exercise per week.