My dad once told me that time flies when you're doing things that are regular, however new, different, and changing periods of time you perceive to be longer as your brain takes longer to process them.
So, if you want a summer that you can remember do something weird. Scuba dive (I actually just scuba dived on the Great Barrier Reef yesterday!), see a movie, cook a wedding cake - go all out! You've got practically 60-70 days to do whatever you can imagine wishing realistic boundaries.
You could:
•Volunteer
•write a book (autobiography?)
•Go somewhere you haven't been before
•Go camping
•Go to a summer festival/music festival/etc.
•Sit down near someone in a public space and start to chat. Doesn't matter if you're scared, they won't know you and you'll become friends! (Can confirm, I have done this!)
•Participate in a water fight.