Some folks value body appearance and health. Some men want to be muscular, look appealing to women shirtless or in a wifebeater, and to be healthy. Some women believe it or not care about their health and weight maintenance. Women especially black and Hispanic have higher rates of obesity and even tho obese and overweight women can pull....a woman keeping her body proportionate, tight and in tact will give her an competitive advantage. Plus women want to look good to men in their two piece swimwear and the tight clothing they were.
Some folks also fear getting fat so they put in time. Also gym can be used as an outlet to receive stress.
I find no issue for those who go regularly and spend over an hour.