At the start of summer (it's not too late now), pick three to five things you want to be accomplish or be better at. Write them down. Now do them every day. Even if only for a few minutes. Here's an example. Suppose you play soccer and want to be able to juggle better by the time of high school soccer tryouts. Every day for ten minutes (or longer if you're are really ambitious), practice juggling a soccer ball. Every day. That's about 70 days. At the end of the summer, you'll be 700 minutes better at soccer juggling. Chances are that's a big difference in skill. Now, consider this--When summer's over, it keeps going in the form of your much improved juggling skill. Summer lasts beyonds its nine weeks.
You can do this with reading, or working out, or singing, or running--whatever your skill or interest. If you are required to read 25 books during the school year, read 5 of them over the summer. This way, the summer will keep on giving and feel like it never ended when your school year is a lot easier because you've already done some of the work. Make some money over the summer, then put it away and use it during the school year when life gets a little dull. You get the idea. You can't actually slow summer down, but you can make it last by using some of your free time to make the effects of summer last throughout the year.
Do one thing you've never done before. Become an expert. Here are some ideas:
Take a day trip to a part of your state you've never visited. Write a review for the local paper.
Take a cooking class or come up with your own recipe at home.
Take lots of pictures and make a scrap book.
Create a book review blog.
Write your memoir.
Plant a herb garden.
Teach yourself a new language.
Read a political book.
Volunteer to cook a meal for a local homeless shelter.
Clean up an old neighbor's yard.
You get the idea. Send me yours.