Did anyone mention about body mass density?

If you have low density, you will naturally float. So all you need to do is concentrate on your swimming strokes, and should pick it up pretty quickly.

If you have high density, you will find it more difficult. The guy who floats with his nose above the water while staying still will be wondering why you are sputtering and choking with water when you stay still - that is because the water is above your nose when you stay still.

So, if you have a higher density body mass, you will find it more difficult.

Besides, some people pick it up quicker than others, regardless of body mass density, like most other things in life,