Although rest and relaxation are naturally the priority, the summer break is also a good opportunity to clear your mind and get back in shape before getting back to business.

Here are a few tips from French personal trainer Yakisan Cagdas to tighten your abs into swimsuit shape while lounging on your beach towel.

Doing this series of four exercises will tone all of the abdominal muscles, from the core muscles to the laterals and obliques.

Exercise 1: Start with some sit-ups

Get into position by lying flat on your back, knees bent with your heels flat, drawn as close as possible to your buttocks. Place your fingertips behind your ears, aligning your arms and shoulders. Your head should be resting on your towel or mat, casting your gaze into the sky.

The exercise entails raising your upper body by flexing your abdominal muscles (always breathe out as you sit up and breathe in as you lie down) as far as possible, chin forward. To get a good workout, do five sets of 15 sit-ups with a 45-second rest between each series. There's nothing better to strengthen your core muscles.

Exercise 2: Strengthen the oblique muscles

Start in the same position, lying on your back with your knees bent and your heels flat. This time, you'll do a "bicycle sit-up" by bringing your left knee to your right elbow until they touch. Your head and shoulders will come up off your towel or mat each time you make a bicycle-peddling motion.

Ideally, you should do five sets of 15 followed by a 45-second rest before switching to your right knee and left elbow. Finish with a set of 40, alternating between the two moves. This is a great exercise for training your obliques.

Exercise 3: Tone the abdominal wall

Turn over and get into "plank position" facing your towel or mat, resting your weight on your forearms and on your toes while flexing your heel. Your elbows should be aligned below the shoulders and your arms parallel to the body. Your body must form a straight line throughout the exercise (the workout will be totally ineffective if your buttocks are too high or low).

All you need to do is contract the abdominals and hold for 45 seconds while breathing in and out before, then relaxing for 30 seconds. Two sets are enough to work out the muscles.

Exercise 4: Harden the lateral muscles

This time, you'll need to get into "side plank position." Your head and shoulders should be aligned with the rest of your body. Pull in your stomach to make your body form a straight line, just as in the last exercise. Your weight will be resting on your forearm and foot, with your hips up off your towel or mat.

The exercise entails raising the hips as high as possible and holding the position. Do two sets of 20 without touching your towel or mat, resting for 10 seconds between each set. Then, switch sides and do another two sets of 20 with a rest in between.