preparing your body for pregnancy?

I read and heard form people that it is good for both future parents to prep their bodies 6 to 3 months prior to TTC: quite smocking and drinking (I don't smoke but DH does), start eating healthy, loose excess weight if necessary. Did anyone go through this cleansing process?

While I was TTC I cut back on caffeine and diet soda type products. I should have lost a solid 15lbs, but never did that.
I didn't drink or smoke so that was a non-issue for me but it is a very important thing to do prior to TTC. You can still have some drinks, but smoking is bad for you regardless.

We have just started TTC and a few months back I quit smoking started taking my vitamins and I am trying to eat healthy (which is difficult because I like everything bad for me lol). The hardest thing for me so far is the caffine. I LOVE diet coke and drinking the caffine free just doesn't do it for me .