The relationship I just left is like smoking cigarettes.  On a day-to-day basis I loved it, and now that I no longer do it, I miss it terribly.  I got sad today when for the first time in two years I checked "single" on the health benefits survey for school; nostalgic when I hear someone ask for a pack of DuMauriers as I wait to pay for my makeup and toothpaste at the drugstore; jealous when I see couples walking down the street holding hands, or a group of drunk kids outside the bar bantering and perfectly insouciant as they suck down that sweet, sweet nicotine. 

But even if being in the relationship/smoking was pleasant on a daily basis, and sometimes even felt necessary, they are terrible for the long term.  

My parents have a fridge magnet that says, "How we spend our days is, of course, how we spend our lives." 

But hold on.  If each individual day with these things is not bad in itself, is pleasant and sometimes even wonderful, how can the aggregate be so bad?  Does one and one and one equal three, or is it simply one and one and one?  And how can one and one and one each be good, but three be cause for concern?