Before I was fit, I was pretty permanently moist, to put it delicately. I was damp under my arms, between my legs, on my forehead, at night and throughout the day; and I got like that with the minimum of movement. I rarely felt cold - in fact whatever the outside temperature I was constantly trying to find ways to cool myself down. Now, I really like it that perspiration is under my control.
Now my sweat is a sort of metric for me. I am dry except when I am exercising. When I am exercising I gauge the intensity of my efforts by how large the pool of sweat beneath me is. And by how soaked my gym clothes are. When you don't want to be sweating, those damp patches beneath your arms are embarrassing. Clothes made from natural fabrics tend to hang on to the moisture you excrete: hence the unsightly display of wetness. When exercising you are expected to sweat, so the clothes you wear are expected to be able to handle the perspiration. Man made fibres are better at not hanging on to the wetness: the theory being that it will pass through the fabric and evaporate. so the most suitable fabric for gym clothes is man made. This process is known as wicking.
Although the one place where seeing your sweat isn't out of place is the gym, gym clothes show the sweat less than clothes made of natural fabrics. But, and this is a big but, when producing large amounts of sweat, they can't get rid of the sweat fast enough to make it unnoticeable to the wearer. It is not the appearance I have a problem with though. If I am in a draught (as in being under the air conditioningor in a cool wind) the wet clothes become uncomfortably cool. Which brings me on to another aspect of being fit. As I said above, I used to tend to overheat. Now, I am more likely to feel the cold: that is, I don't tend to feel hot in hot weather or when working out, but I really feel the cold, as in cold winds or weather, so I notice the cooling effect of sweat laden clothes.