Consider simple whole foods. Consider raw foods.
You don't have to heat up water or fire up a stove to make a robust green smoothie or fruit smoothie for one. PB&J sandwiches are still simple and quick.
Try gaspacho soup or vichyssoise. You can make the soups and freeze them, and just let them thaw when you want to eat them later. There are lots of cold soup recipes out there.
If you need a snack: peel a banana, or eat apples, berries, melons, citrus fruits etc.
Chop up and snack on some vegetables (cucumbers, bell peppers, celery, carrots cruciferous veggies, whatever you like)
One of my favorite summer dishes is fruit salad:
Mango, pineapple, kiwi, strawberries, blueberries, blackberries, cherries, bananas, peaches.
Mix separately: the juice of 1 lemon, 2 TBSP maple syrup, 2TBSP orange or peach liquor (alcohol optional), 1/4 tsp cinnamon. Add to peeled, diced, sliced, chopped fruit (except I leave the berries whole) and if you like/are not allergic to nuts, add some walnuts or pecans- they add a nice texture and it is good to have some fat to help absorb many of the nutrients from the fruit.
Nuts. You can get a great variety of nuts for reasonable pricing at Trader Joe's. I make a custom trail mix of dried fruits and nuts.
If you are concerned about life of greens and produce, try something like this: