Smartphones are great for many reasons but with summer right around the corner, bet you didn't know your smartphone could be your best workout buddy, too. If you care about things like looking good on the beach, there are a few apps out there that will surely help you to get fit, simply by using your smartphone.

One favorite is the Nike Training Club, free on Android and iOS. According to the New York Times, it has a simple, clean interface, so you can exercise without distractions. The home page has a summary of your training performance and a menu bar that takes you to pages with more details on your previous workouts. There's also a rewards page where you can earn digital badges for completing workouts.

To begin your workout, you click the Get Workouts button, or pick Quick Start and choose the workout you did previously. The workouts vary, depending on whether you want a leaner body or a stronger one, for example. When you choose an activity the app inquires about your experience level (beginner to expert) and offers a list of different exercise styles. As an example, the beginner level's Get Lean workout has a 30-minute "sweat and shape" and a harder 45-minute "crunch and burn" workout.

Before you begin, the app lists the activities it will ask you to do. You can click on these to get step-by-step advice, with images, to help you do them correctly. Or you can watch a professional demonstrate the moves in a short video, according to the The Times.

When you begin a workout, the app gives you a spoken summary of what's ahead, and then starts a large on-screen clock. While you're exercising, the app speaks aloud at key moments to give you tips or let you know how much time remains in the exercise. In the Straight Leg Kicks exercise, it reminds you to "roll up on the ball of the standing foot when you kick." You can exercise to this voice alone, or listen to music from your device library with the coaching voice superimposed over your music.

The app has a nice list of different workouts and includes examples from famous athletes.