Why would cake beat exercise in a fight?

I'd like to make one thing quite clear. People who say exercise is fun, or that they enjoy working up a sweat, or that they work out every day, are completely and utterly stark raving mad.

I speak from experience. 

I understand that I can't just sit around and eat cake and expect to be thin, so today I decided to do some exercise. I got on the exercise bike that's been used as a coat-stand in our living room since last autumn and I cycled for half an hour.

I huffed and I puffed and I got sweaty. I felt like my glasses were definitely going to fall off my face from the perspiration. My back felt like I'd poured a litre of water over it. It was not a pleasant experience.