It can be pretty annoying to practice in a crowded class where you don’t have a whole lot of space around you. Teachers will usually say something like “Just remember that your mat is your haven.” Maybe it works for you, maybe it doesn’t, but obviously the preference for most of us is that feeling of ease and freedom that comes from having ample room around our mats.
But there is a good psychological reason to embrace the times where a class is full and you feel that anxiety bubbling up as your personal bubble is infringed upon. Different cultures have different unspoken rules for where those bubbles end and begin. In many Latin cultures, for example, the personal bubble is almost non-existent, and there’s a real advantage to having that mentality in our modern world.
Most of us are urban dwellers these days, and whether it’s the bus, subway, movie theater, waiting in line, or whatever other activity you’re doing in public, there are going to be times when people are basically breathing down your neck. Since practicing yoga is probably a calming, peaceful, joyful experience for you, it’s a good sphere to acclimate yourself to people seeming too close to you, realizing you can deal with it. When it happens in other situations, go back to your breathing and summon up the picture of the overcrowded class that you handled with aplomb and you’ll instantly feel a lot better.