Developing your brain is just as important as developing your body. Numerous studies show how physical activity enhances brain functionality.

While you remember to fit a workout in every day or so, working out your brain is more challenging. The good news is, you can exercise your brain with apps on your phone. Many apps are cheap (or even free), easy to use, and you can pull them out whenever you've got some downtime.

Here are a few of my favorites.

Elevate

Available on Android/iOS, Elevate offers mini-games that put your brain to the test. The app's activities test focus, memory, general comprehension and math skills.

Elevate can be addictive. Fortunately, the difficulty ramps up as you progress through the 30 unique challenges. So the more you play, the more you think.

Peak

Peak has great user experience. This app is full of brain-boosting mini-games that enhance your understanding of language, memory and boost attention span. The games have just enough variety to keep you interested. The best part is Peak is totally free on iOS and Android.

Cognito

Available on android, Cognito is a story-based brain exercise app about a global spy mission. Cognito improves logic, memory and vocabulary through fun word-based, mini-games.

The app also keeps detailed track of your statistics to gauge skill improvement. Cognito even incorporates information from Apple's Health app like sleep quality and steps taken per day. Cognito is available at no cost, but you have to pay a small subscription fee for access to the entire collection of games.

Fit Brains Trainer

Fit Brains Trainer has nearly three dozen games divided up into specific groups to maximize the efficacy of mental workouts. The app alternates the order which the games are presented to keep the experience fresh. The games test and enhance language skills, concentration and memory.

These mental challenges are even customized to your emotional intelligence. The app also allows you to log in from your computer to finish your game if your phone dies.

Lumosity

Available on iOS/Android, Lumosity is also free. The app's mini-games are served up in a mix-and-match fashion. Lumosity features extensive user statistic tracking to show how performance improves as time progresses.

You will have to pay a fee to unlock additional games and features, but most people can enjoy the basic version alone.

While you're working out your brain, don't forget to work out your body, too. Test your fitness level with my Fitness Level Body Challenge below.