Seriously, people. Let's set aside all the craziness about getting skinny, and what you're supposed to look like, and guilt, and extreme exercise programs. There's a place for some of that, and that's not here right now.
Let's get real for a second.
Everyone has a body.
Everyone wants their body to work, today, and for as long as they're alive.
Nobody wants to be in pain, or unable to move.
Everyone wants to have enough energy to do what they need and want to do in a day.
You brush your teeth because you don't want them to fall out, and because you don't want toothaches, or bad breath. You do this every day. It is considered basic maintenance. You get your oil changed, because you want your car to keep running smoothly and last a long time without giving you problems. This too is basic maintenance.
Exercise is basic maintenance for your body.
It doesn't have to be hard. You don't have to get super sweaty. You don't have to hate it. But you do have to move to keep your body working. Period. There's no way around it. This needs to be part of your daily routine.
There is no reason for an able-bodied person to ever spend 24 hours not moving beyond couch to desk to bathroom to bed. You can walk, you can dance, you can stretch, you can bounce on a trampoline, you can ride a bike. You can also do the harder and more intense things, if you're interested in doing so or have fitness goals beyond "survive and feel good and live a long life without my body breaking down on me." But if you do not move on a daily or nearly daily basis, your body will stop working as well as you'd like it to, and eventually it will break. Just like your teeth will rot if you do not brush them, and your car will break down if you do not change the oil.
So if nothing else, make sure you spend an hour a day (not necessarily at once - you can add up five or ten minutes here and there) moving. Out of your seat, out of bed, off the couch. Walk around the office, go outside, ride your bike, turn on some music and dance around, clean your house, dig in the garden, play with your kids or pets... do something. Anything. This is basic maintenance, bare minimum for survival and general health.