With summer winding down and the next college semester on the horizon, it’s almost time to snap back into school-mode. Are you ready?

If you’re like many students who are suffering from summer brain drain at this point, then that answer is no. You’re not ready, not even close.

You’re like, “College? I only know Netflix.” And what is this summer brain drain you speak of?

This concept, or summer slump, refers to the learning loss that inevitably happens for students over the long, hot summer. In other words, your brain turns to mush after vacations, video games, excessive alcohol, or whatever you spend your time doing this summer that doesn’t require mental exertion.

If you think about it, you probably weren’t studying up on art history during your family vacation to Florida. And I don’t blame you.

But three months of little brain activity causes problems. This creates a dull, lazy brain, which makes it ten times harder to get into the swing of things when school starts.

Writing that first paper or studying for the first test will seem impossible if your brain took a long hiatus from learning.

Also, the progress you made in a subject during the spring can be lost when you come back in the fall. If you were getting close to proficiency in Spanish and then didn’t speak a word of it all summer, your fluency went backward.

On the other hand, summer is meant to be enjoyed so don’t get too down about this. What you’ve done up to this point in summer is done. And we can’t go back in time now.

However, you can make progress to sharpen your brain and get back up to speed during these last few weeks before school starts.

To accomplish getting your mind back into shape, I came up with some ideas.

1. Find a new hobby

It’s super difficult to pick up a new hobby with school on your plate. When your day is filled up with responsibility after responsibility, there’s no extra time to pick up playing the guitar.

This isn’t the case during the summer. Find a new hobby that you’ve always been interested in trying. The time is now.

Besides the entertainment in doing this, challenging your brain to learn the ins and outs of a new hobby is an excellent way to keep your brain sharp leading up to school. It’s a win-win.

2. Take a free online course

Imagine going back to school in the middle of a mission to learn a new skill. The fact you’re pushing yourself will be cool when you tell your friends about it and it will build self-confidence.

Want to know how to code an app? Learn French? Or take a random course in anatomy? The opportunities to get started are endless when you read this guide.

I always say knowledge is power, and this is free knowledge, so it’s even better. Plus, when you see your friends at school, how else are you going to brag about studying at Harvard over the summer with a straight face?

3. Watch TED Talks

The fact that we have free access to TED Talks is unbelievable. These world-renowned experts offer their life’s work in a short discussion for your curiosity and understanding. Take advantage of it!

If you only have a week before school starts, listen to two TED Talks a day up to then. Or do one better by talking to your friends and family about what you learned to get different perspectives.

These short, powerful TED Talks can open your mind to a whole different perspective of something. That’s the opposite of summer brain drain.

4. Read a book or two

I may have been biased when writing this one because I love to read.

Reading is so good for your brain! It helps you learn from other people’s mistakes, improves your communication skills, exercises your brain, and a book before bed helps you sleep at night.

If you’re looking for something to read, check out my list of 15 best books for college students.

5. Play brain-training games

This sounds silly, and yet it works. Brain-training games like Luminosity or Fit Brains Trainer will effectively test your memory, speed, problem solving, and attention.

For those people on their phone all day, these mental agility games might be the only option they consider.

And you could always go old-school and do a crossword puzzle or play Sudoku.

Do one of the six activities listed before school starts and you’ll get off to a fast start this semester because your brain will be ready to go from day one!

6. Start a side business

If you’re ambitious and want a big challenge, you can spend your free time to start a side business before college starts.

This post outlines all the ideas—from social media consulting, IT service, photography, and more—you can do that require little to no formal education. So you can start today, if you wanted.

Then, use the momentum and what you learned in the last few weeks before school starts to build up your business during the school year and see how far it can go. At the worst, you’ll come away with a valuable learning experience and hopefully some extra cash.

Remember, you only get one brain, so keeping it sharp is vital.

What do you spend your time doing this summer?