Three words - equipment, exhale, relax. We all have that problem when we are new divers and on occasion even after we’ve gained experience. Realizing that will be a good start toward becoming a more relaxed diver. Are you using off the shelf equipment? If you fit between the stock sizes, you may be using a BC that is too large allowing it to float upand and making it dificult to adequately exhaust the air. Talk to your dive shop - manufacturers often have sizes that are not normally carried in the shop, such as ML, and it is a simple matter of having the shop order it. Also all waters vary in the amount of dissolved solids, and that will affect your bouyancy. If you usually dive in a freshwater lake that is fed by surface runoff, it may have only 100 - 200 ppm of dissolved salts, on the other hand a spring fed quarry may be more brackish, containing 800 to 1500 ppm. Understanding this allows you to adjust your weighting without feeling like you are somehow doing something wrong, and that will make it easier to relax.