Summer School for Entrepreneurs Is Now in Session Extra reading and training could help you get ahead this season.

In high school, summer school had terrible connotations, like failing algebra. Summer school was always reactionary, used to make up course credits.

You might be out of school now (some of us may have never needed it), but that doesn't mean you can't use the summer to check out new resources for training and reading.

Summer school for entrepreneurs is now in session. Yes, I know it's almost August, but pretend you're on the quarter system and that the fall session starts later.

Here are three treasure troves that can help you get ahead in whatever field you may be in:

Related: Why an Entrepreneur's Place Is in the Classroom

1. Sales and marketing

Instructor: Noah Kagan

Noah Kagan, one of the first employees at Facebook, and is now the "chief sumo" at AppSumo, a company that distributes digital tools that help people succeed in the workplace. In addition, he pens OkDork, one of my favorite sites about sales and marketing.

I was lucky enough to find his blog right around the time I began my sales career at Waze. His insight and advice greatly advanced me beyond sales pup status.

One of the challenges of selling a new product is that not many people have heard of it. So in order for me to get chief marketing officers to take my calls or reply to my emails, I had to learn to write compelling and creative messages and be clear and succinct on the phone.

His tips and tutelage on cold-selling approaches have helped me land meetings and close business deals.

His blog is a great resource for anyone beginning a career in sales and marketing. In addition, he teaches various courses via email and through AppSumo that are well worth your time.

Related: How Entrepreneurs Can Read to Lead

2. Literature

Instructor: Ryan Holiday

I used to think that I read a lot. Then I met Ryan Holiday.

The author of The Obstacle Is The Way and a former director of marketing at American Apparel, Holiday says he reads more than 250 books a year.

Subscribe to his book list via his blog to receive great recommendations.

It was through his list and blog that I came across two of my now-favorite books Virtues of War and Cyrus the Great.

His blog carries content on life, business and personal growth. In one of my favorite posts, he shares his system for extracting, storing and retaining what you read by using what's called a commonplace book.

Related: The Two Simple Things Everyone Needs for a Healthy Body

3. Physical education

Instructor: Adam Gilbert

When I started lifting weights five months ago, I struggled to squat 90 pounds. Now, I'm lifting 200 lbs. easily. What changed?

I signed up for Adam Gilbert's My Body Tutor program.

Gilbert or one of his tutors will work with you day by day, meal by meal and workout by workout to help you achieve your fitness goals.

In my case, he put together a comprehensive workout plan designed to help me become stronger and leaner.

In addition, he helped me start making the right diet choices. Before I consulted him, I was wondering why I wasn't shedding any weight even though I played soccer or ran six times a week.

Not only did he point out that I had to incorporate lifting into my regimen, but he also saw that my food portions were way too big. I made one simple change and now I'm steadily adding muscle to my frame.

Gilbert's site charges a monthly fee, but if you want to receive daily feedback and a plan specific to your goals, then signing up for the My Body Tutor program is a great investment.

There are an infinite number of resources, blogs and courses to consult when you're looking to better yourself. These three have helped me tremendously. So while you wait for the newest season of Game of Thrones or the start of England's Premier League, check out these sites and blogs.

Related: The Smartest Long-Term Investment is You

Related: Entrepreneur Bookstore