I could eat whatever I liked and stay effortlessly slim, without an exercise routine, until I was in my late 20s. I was so tiny that people would regularly ask what I did to maintain my figure.
I'm in my mid-40s now and I still eat whatever I like. The difference is I'm now a size 18.
If I'd always had to work at staying slim I might have a different mindset and be slimmer. Realistically I love good food too much to have the discipline to change. Being fat gets me down, but cooking gourmet meals and eating out are two of life's greatest pleasures and the prospect of giving them up/cutting down makes me feel far more miserable. I don't eat bread, desserts, or processed food, but not because of the calories, I just don't personally enjoy them. I dread to think how huge I'd be otherwise.
I walk pretty much everywhere but don't do any specific exercise. I used to do circuit training but found this made me ravenous so I piled on the pounds!
The majority of my slim friends are constantly in a cycle of losing weight with Slimming World, gaining a stone when they stop, berating themselves then repeating the process again. I've tried their slimming world meals and they're so flavourless and unsatisfying that they make me want to weep.
I have one friend my age who is effortlessly slim - she's vegan, has never given birth, and rides horses several times a week.
The comments about skipping breakfast are interesting. I've always abided by 'eat breakfast like a king, lunch like a prince, and dinner like a pauper' but I can't deny that everyone I know who skips breakfast is a lot slimmer than me!