Looking to get fitter and stronger? Want to last longer in the gym? If so, focus on improving your fitness level. The key is to gradually increase workout duration and intensity. Run instead of walking, swap cardio for HIIT, and lift heavier weights. Contrary to popular belief, getting fit doesn't require hours of cardio. It's how you train that matters. Your diet can make a difference too. Pre- and post-workout nutrition play a key role in exercise performance. So, here are five foolproof ways to boost your fitness level: Stretch for Increased Flexibility The first step is to increase your flexibility and range of motion. This can be done through regular stretching. Passive and dynamic stretching are particularly beneficial. Do it before and after exercise, during your lunch break, or on your rest days. Make a habit out of stretching your muscles daily. This simple practice will improve your athletic performance, mobility, and muscle function. In the long run, it lowers injury risk and boosts circulation. You'll move around more easily, enjoy more intense workouts, and experience less pain and muscle soreness. Try Cross-Training Include two or more types of exercise into your routine. These can include strength training, cycling, swimming, running, CrossFit, or rowing. The human body is very efficient at adapting to exercise. If you always run on the treadmill or lift weights, you'll hit a plateau. Keep your workouts varied to challenge your muscles and become more athletic. For instance, many football players lift weights to build lower body strength. MMA fighters do cardio to lose fat and boost their endurance. You can do the same in order to keep your body guessing and prevent plateaus. This principle is known as cross-training. Take Shorter Breaks between Sets Most gym goers rest for 30 to 90 seconds between sets. However, if your goal is endurance, take shorter breaks. This will keep heart rate up and boost your stamina. It's also a great way to rev up your metabolism and shock your muscles. If you rest for too long between sets, your muscles get cold, your heart rate drops, and you lose the pump. Increase Workout Duration and Intensity Your body can only improve if it's pushed beyond what its limits. That's why it's harder to boost your fitness if you're already in a good shape. Constantly change your workout variables, such as intensity and duration. Let's say you can do cardio for hours. Replace it with 10-15 minutes of HIIT or full body circuits. Evidence shows that high-intensity interval training can yield dramatic results in exercise performance in just two weeks. If you're into strength training, lift heavier weights. Increase the volume by eight to 10 percent from one session to the next. Experiment with different rep ranges, stances, and grips. As intensify goes up, volume should come down. Try New Exercises When it comes to workout performance, routine is your worst enemy. Think of the gym as a huge playground. Try new exercises, swap dumbbells for kettlebells, and replace gym machines with free weights. Incorporate exercise balls, suspension training, and chains into your workout. Use a foam roller to boost your flexibility and overall endurance. As you see, the whole point is to keep experimenting. This will prevent your muscles from adapting to exercise, leading to faster gains. Moreover, it improves your functional fitness and helps you break through plateaus.