However, there are some things I suggest you consider doing that will give you a broader perspective on the study and practice of law, that can also be interesting and enjoyable activities the summer before you start law school. If you are working and simply don't have time, don't worry. You can do a bit of these now and a bit after school begins. And if you don't get to them, you aren't doomed. Think of these as sort of legal "personal development" activities.
1. Go to Court. Even if you never plan to litigate, visiting a courtroom and observing a trial will help you to understand the United States legal system. And, depending upon the cause of action, you may find it enjoyable if not downright entertaining. To some extent, trial is theater and each side is doing their best to convince someone of their client's positions. If you decide to do this, be sure and check with the court to make sure you follow proper protocol. The court clerk's office can help you in this regard.
2. Talk to Lawyers. Find some time to talk with lawyers who practice in different areas, such as litigation, corporate transactions, intellectual property, family law, estates, and the like. You may have to offer to take a busy lawyer to lunch, but if you approach these people appropriately, you will likely find some generous people who would love to help you understand what they do. You might look at a local firm's website and start by sending an email to the lawyer. And although not your primary objective, this is also a good opportuity to network a bit.
3. Read the United States Constitution. Okay, this one requires a bit of work. But considering that it is the foundational document of our legal system, it's worth the read. And besides, it's actually not that lengthy. Read it in order to understand the division of power among the various branches of government, and to understand how what we call "individual rights" came to be by virtue of the various constitutional amendments.
4. Read Some Books About Law. There are hundreds of great fiction and non-fiction works about the practice of law. I won't go into any more detail than that, and to suggest that you look at the LSAC reading list, as well as ABA suggested reading. Additionally, chances are that your law school also has a suggested reading list. But there are some great books out there that will give you a good perspective on law practice, that won't require the kind of intensity you'll face in law school.
In short, take some time to familiarize yourself with basic concepts, but do so in such as way that will interest you. Presumably, law practice will be your life's work. And it's a great field, with all kinds of fascinating twists, turns and concepts. Immerse yourself in the practice. Soon, and before you realize what has happened, you will be "thinking like a lawyer", passing the bar and practicing. Now is a great time to begin developing the breadth and depth that characterize great lawyers.