To tell if you're working out at a proper intensity, use the talk test while you exercise. Your workout should be intense enough to make you breathe deeply and to make you feel a little winded. But, you should still be able to carry on a conversation while you exercise. If you don't have enough breath to get the words out, you're working too hard. So slow down a bit. Back off until you can speak comfortably. On the other hand, if you don't feel winded at all, you can increase your intensity by going faster. Another way to increase your intensity is by walking uphill rather than on a flat surface.
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