The benefits of exercise are well known but if you are starting a fitness plan you may experience fatigue. Fatigue is your body's way of helping you adapt to a fitness regimen and making you aware that you have reached your limit. So, while you can’t completely avoid exercise fatigue, the following healthy lifestyle changes and tips can help keep you from hitting a wall in your workout.

1. Eat a well-balanced diet. Your daily food intake should include complete proteins (such as meat, eggs and milk, or quinoa, chia seeds and soy if you follow a plant-based diet), fruits, vegetables and carbohydrates. The amount of carbohydrates you eat should be about 40-60% of your caloric intake for aerobic athletes and 30-35% for anaerobic (nonaerobic) athletes. Protein consumption should account for about 20-30% of your caloric intake and healthy fats should make up the remaining 10-15%.
2. Time your food intake to your exercise. Eat a light meal or snack about two hours before working out. Try to avoid working out on a full stomach or an empty stomach. Also make sure to eat within one hour after your workout. This meal should be high in protein as it will aid muscle recovery and help your muscles repair from the stresses that exercise places on them.
3. Drink more water. Drinking water throughout the day and during exercise is crucial to prevent dehydration and muscle fatigue. Try to drink ten to twelve 8-oz glasses of water daily and 7 to 10 ounces of water every 10 to 20 minutes while exercising. This will replace the water that is lost due to sweating.
4. Rest and recover. Complete a warm-up and cool down for 5 to 10 minutes each time you exercise. Start off slowly and steadily increase the intensity of your workouts so that your muscles are gradually challenged and can build over time. A dynamic warm-up, such as foam rolling, dynamic stretching and mobility exercises, is a great way to get the body primed and ready to move.
Allow adequate rest between workout sessions and strength repetitions. Make sure the rest break is enough to catch your breath between exercise sets. Listen to your body; fatigue is a sign that recovery has not taken place yet. If that is the case, then perform active recovery, which means participating in low-impact, low-intensity exercise such as walking, light swimming or yoga. Do not return to higher-intensity exercise until you feel fully recovered and recharged.
Source: https://www.hss.edu/article_fatigue-from-working-o...