This picture alone should be all five reasons.
1. Summer movies. Don't we all love the hundred of movies coming out during the summer? It's like every weekend, a four new movies come out for your enjoyment. Don't enjoy the cheesy predictable plots? You could still enjoy sitting in a air-conditioned room with friends for two hours right? Unless you hate being cool, and hanging out with friends.
2. Summer vacation. I know that some people don't get the luxury of a three month break from their work, as kids, teens, and young adults do from school. (Not to mention school teachers!) But for the people that do get to enjoy the vacation, they'll get some time away from the stresses of life, and enjoy blissful youth while it lasts.
3. The heat might help you lose weight. With the constant heat, your body will constantly be in a battle for its life to maintain body temperature. While that occurs, your body will use up calories, which will help you passively use more calories sitting around doing nothing, than during early spring or fall. Obviously, I don't mean that you'll be dropping pounds by simply sitting there, but you'll certainly lose a few extra calories.
Now you can be slightly less self-secure about yourself!
4. Fruits are more readily available. When it's winter, you can expect to pay at least five hundred dollars for a pound of pears. (What? You get them cheaper? Who's your pear guy?) During the summer, you can expect generally cheaper costs for fruits, since they're being readily grown. Now who has an excuse for not eating healthy? Another side-effect of having more fruits, is that lifestock will have greater access to fresh fruits, to oppose to freeze-fry feed, which might lead to healthier, more delicious meat for you meat lovers.
5. Excuses for basically anything. You can use the heat as an excuse for pretty much any guilty pleasure you may participate in. "That's your seventh Popsicle Jenny! Think of the sugar content!" "It's a freaking heatwave John! Also, I'm breaking up with you."
If you look at summer at a more positive point of view, you summer haters might have a change of heart. Even if it takes a "long look". For everyone else, there's winter.
And for everyone else, there's Neptune.
Protip: Sweating too much? Theoretically, cold water closes your pores, the same pores that sweat comes out of. Hint, hint.