Sitting tightens the calves too, especially if put your heels on the chair legs to prop them higher. Zero drop shoes, lowering every chair as much as possible, sitting on even lower things, and the "third world squat" all help. I saw my daughter squatting that way and it made me look it up. Adults should be able to do it too. Squatting desks are great. Also, dont do your introduction to CrossFit at a competitive box. Or don't do it at all and do something like starting strength or stronglifts.