Why do we continue to do the things that is bad for us?

I'm a little scared about starting this. :(

Since February, I've been eating "badly" and well, it's not good. I have put on a stone and a half and I am the biggest I have ever been. My knees creak slightly, I suffer from chronic lower back pain which is only satisfied temporarily by bending my body in weird shapes. I am literally short of breath as I type this as I know that it is difficult addressing the truth. The truth is that I don't work. I have literally stopped working. I go into work and appear to be working but I'm not, I'm a slave to google and my day will just be procrastinating continuously on end.