I grew up in an era when guys were much more comfortable with nudity in male-only environments such as locker rooms, camping, and shared living arrangements, which became a part of my every-day life starting in college. A few more bashful guys would face away while changing, etc., but most of us had no inhibitions about interacting with others in situations where our dicks were on full display. It felt incredibly manly to show off that I had zero inhibitions about other guys seeing my penis.
Fortunately, I've continued to work out in gyms with open showers and have a set of friends who share my comfort level with nudity, so I'm able to still maintain these habits today (well, not during the lockdown, of course). For example, since we have open showers, thus normalizing locker room nudity, I don't feel the need to cover my penis when I walk between my locker and the shower.