The energy you bring to a workout depends on what you eat, when you eat it, how hydrated you are, and whether your body has the raw materials it needs to produce fuel at the cellular level. Most people searching for this answer are dragging themselves to the gym or skipping sessions entirely because they feel flat. The fix is almost always a combination of nutrition timing, hydration, and a few simple habits that prime your body and brain to perform.
Eat the Right Foods at the Right Time
Your muscles run on stored carbohydrates called glycogen. When those stores are low, whether from skipping meals or eating too little, your workout feels harder than it should. The goal is to top off that fuel tank before you train.
Aim to eat a meal or snack combining carbohydrates and protein one to four hours before your workout. The exact timing depends on how your stomach handles food during exercise. A full meal three to four hours out works well, while a smaller snack like a banana with peanut butter can work as close as 60 minutes beforehand. If you train first thing in the morning and can’t stomach a meal, even a piece of toast or a handful of dried fruit 20 to 30 minutes before can make a noticeable difference compared to training completely fasted.
The type of carbohydrate matters, too. Slower-digesting carbs (oatmeal, whole grain bread, sweet potatoes) outperform quick-sugar options like white bread or candy. In a cycling study, athletes who ate a low-glycemic meal 45 minutes before exercise completed a 40-kilometer time trial about three minutes faster than those who ate a high-glycemic meal. The reason: slower carbs provided a steadier stream of fuel throughout the session instead of a spike and crash. A good rule of thumb is roughly 1 gram of carbohydrate per kilogram of your body weight in that pre-workout meal, so about 70 grams for a 155-pound person.
Hydrate Before You Feel Thirsty
Dehydration is one of the fastest ways to tank your energy. Losing just 2% of your body weight in fluid, which is about 3 pounds for a 150-pound person, measurably reduces aerobic performance and makes your brain feel foggy. You can hit that level surprisingly fast, especially in warm environments or if you haven’t been drinking water consistently throughout the day.
Start hydrating well before your session. Drinking 16 to 20 ounces of water in the two hours leading up to exercise gives your body time to absorb it. Sip another 8 ounces in the 15 minutes before you start. During the workout, aim for about 7 to 10 ounces every 10 to 20 minutes. If your workouts regularly last over an hour or you sweat heavily, adding electrolytes helps your body hold onto that fluid instead of flushing it straight through.
Use Caffeine Strategically
Caffeine is the most well-studied legal performance enhancer available. It works by blocking the brain’s sleepiness signals and increasing the release of stimulating chemicals that make effort feel easier. The traditional recommendation is 3 to 9 milligrams per kilogram of body weight, but recent research shows that even very low doses, as little as 0.9 to 2 mg/kg, improve strength, muscular endurance, and movement speed to a similar degree as higher doses.
For a 155-pound person, that low-dose range translates to roughly 60 to 140 milligrams, which is about one small to medium cup of coffee. Drink it 30 to 60 minutes before training to let it peak in your bloodstream. If you’re sensitive to caffeine or work out in the evening, even a half cup or a small green tea can provide a noticeable boost without wrecking your sleep later.
Do a Dynamic Warm-Up
Jumping straight into heavy sets or intense cardio when your body is cold is a recipe for sluggishness. A 5 to 10 minute dynamic warm-up (leg swings, arm circles, bodyweight squats, light jogging) increases blood flow to your muscles, raises your core temperature, and speeds up the chemical reactions that produce energy. You’ll notice the shift when you start to lightly sweat: that’s your body signaling it’s ready.
This isn’t just about injury prevention. Warming up improves oxygen delivery to working muscles, speeds up nerve-impulse transmission, and increases your rate of force development. In practical terms, your first working set will feel significantly better than it would if you walked in cold and loaded up the bar.
Play the Right Music
This one sounds trivial, but the research backs it up. Music above 120 beats per minute, think uptempo pop, hip-hop, or electronic music, improves workout performance without making the effort feel any harder. In a study on high-intensity rowing intervals, fast-beat music (averaging around 134 BPM) led to better output with no increase in how difficult participants rated the exercise. Your brain essentially gets distracted from the discomfort and locked into a rhythm.
Build a playlist before you train. Matching the tempo to your activity helps: faster BPM for lifting and sprints, slightly slower tracks (around 100 BPM) for warm-ups and cooldowns.
Check Your Iron and Magnesium
If you’re eating well, sleeping enough, and still dragging through workouts, a micronutrient deficiency could be the problem. Two of the most common culprits for exercise-related fatigue are iron and magnesium.
Iron carries oxygen to your muscles. When your stored iron (measured as ferritin in a blood test) drops too low, everything feels harder. A ferritin level below 30 ng/mL is the most widely accepted threshold for deficiency in adults. Some research suggests that even levels below 50 ng/mL can cause unexplained fatigue, particularly in women. If you menstruate, eat a plant-based diet, or train at high volumes, your risk of low iron is higher. A simple blood test can identify the problem.
Magnesium plays a direct role in how your cells produce energy. Your body’s primary energy molecule, ATP, has to bind to magnesium to function at all. When magnesium is low, ATP production slows down, and you feel it as fatigue, weakness, and muscle cramps. Leafy greens, nuts, seeds, and dark chocolate are good dietary sources. Many active people still fall short, and a magnesium supplement taken in the evening can improve both energy levels and sleep quality.
Fuel During Longer Sessions
If your workouts last under an hour, pre-workout nutrition and water are usually enough. But for sessions stretching past 60 to 90 minutes, your glycogen stores start running low and you need to refuel mid-workout.
For exercise lasting one to two hours, aim for 30 to 60 grams of simple carbohydrates per hour. Sports drinks, energy gels, or even gummy bears work because your body needs fast-absorbing sugar at this point, not slow-digesting whole grains. If you’re going past two hours (long runs, endurance cycling, extended hikes), you can push intake up to 60 to 90 grams per hour as long as your stomach tolerates it. Start fueling early in the session rather than waiting until you feel depleted, because by then you’re already behind.
Sleep Is Non-Negotiable
No amount of caffeine or pre-workout nutrition can overcome chronic sleep deprivation. During deep sleep, your body repairs muscle tissue, restores glycogen, and regulates the hormones that control energy and appetite. Consistently getting fewer than seven hours per night reduces reaction time, lowers motivation, and makes the same workout feel significantly harder.
If you find yourself needing to “get energy” for every single workout, the problem may not be your pre-workout routine. It may be that you’re under-recovered. Prioritize 7 to 9 hours of sleep, and if your training schedule forces early mornings, shift your bedtime earlier rather than just hoping willpower carries you through.