You can injure yourself in any activity, but CrossFit is more safe than many activities people perform every day. We like to work with people in 3 stages. First: mechanics (learning how to do the movements with correct technique), Second: Consistency (the ability to do the movements over and over again with safe and relatively efficient technique), Third: Intensity (the speed at which you do the movements). One does not come before the other. We always start with Mechanics.