The only thing I find different in Summer months is diet or possibly activity level. In the winter I tend to make more comfort meals - pot roast, roast chicken, vegetable soup. In the Summer, we grill out a lot, eating fresh corn, etc. I can have it, but in moderation. Our entire schedule just seems busier - from our calendar to being more active, since daylight is longer.
Personally, I'm more a hermit, Winter-loving type person. LOL Give me a good snowstorm, a roaring fire and movie (or favorite TV show, such as Lost....need I say more!) and I'm very content. My gut probably is content too.
Hubby and I live in Ohio and I often joke when we retire that I want to move north. Not south - LOL! I should have learned to snow ski, I love Winter so much. he he
Could that be it - the business of Summer and fresh Summer-like produce? You did mention leafy greens.....that could be one component for the change(s) you've noticed.