To weigh or not to weigh

I weigh myself every morning. I know there are some people that think that while you are watching what you eat you should stay away from the scale. I use to never weigh myself. One day I was at my sister's home and I got on her bathroom scale. I was shocked at what I saw. I was at least 30 pounds more than I thought I was. I never owned a scale up until then and I went right out and bought one. I have dropped 40 pounds since then (over 2 years ago) but now I do watch my weight daily.