The most reliable way to get energy for exercise is to fuel properly beforehand, sleep enough to let your muscles restock their energy stores, and stay hydrated. If you consistently feel too drained to work out, the issue is almost always one of these three factors, sometimes combined with an underlying nutritional deficiency. The good news is that each one is fixable with specific, practical changes.
Eat the Right Foods at the Right Time
Your muscles run on stored carbohydrates called glycogen. Eating carbs before a workout can increase muscle glycogen stores by roughly 42%, which directly translates to more available energy during exercise. The key variables are what you eat, how much, and when.
Aim for about 1 to 2.5 grams of carbohydrates per kilogram of your body weight before a workout. For a 150-pound person (68 kg), that’s roughly 70 to 170 grams of carbs, depending on how intense and long your session will be. A banana with oatmeal and honey, a bagel with jam, or rice with a bit of chicken all fit the bill. The carbs provide fuel, and a small amount of protein helps sustain your energy without weighing you down.
Timing matters more than most people realize. Eating 2 to 3 hours before exercise gives your body time to digest, stabilize blood sugar, and top off glycogen stores. Studies consistently show better performance with this window compared to eating right before a workout. If you eat within 30 to 60 minutes of starting, your blood sugar and insulin are still elevated, which can actually cause a temporary energy crash once you begin moving. If you’re short on time, a small, easily digested snack like a piece of fruit 20 to 30 minutes out is a reasonable compromise, but the 2-to-3-hour window is the sweet spot.
Sleep Is Where Your Energy Gets Rebuilt
Poor sleep doesn’t just make you feel tired. It physically depletes the fuel your muscles need. After 30 hours of sleep deprivation, muscle glycogen concentrations dropped by about 24% in one study on athletes, falling from 274 to 209 millimoles per kilogram of dry muscle weight. That’s a significant reduction in your body’s stored energy, and it happened independent of diet. The athletes also reported higher perceived stress and performed worse in repeated sprints.
You don’t need to pull an all-nighter to feel this effect. Chronically getting six hours instead of seven or eight creates a slow glycogen deficit that accumulates over days. If you find yourself dragging through workouts despite eating well, sleep is the most likely culprit. Seven to nine hours consistently does more for workout energy than any supplement on the market.
Drink Enough Water Before You Start
Losing just 2% of your body weight in fluid, about 3 pounds for a 150-pound person, measurably impairs both aerobic performance and mental focus. That level of dehydration is easy to reach if you haven’t been drinking water throughout the day, especially in warm weather or after a morning cup of coffee.
A practical target is to drink 16 to 20 ounces of water about two hours before exercise, then another 8 ounces in the 15 minutes before you start. If your urine is pale yellow, you’re generally in good shape. Dark yellow means you’re already behind.
Use Caffeine Strategically
Caffeine is the most studied and most effective legal performance enhancer available. It improves muscular endurance, power output, sprint speed, and how hard the exercise feels. The effective dose is 3 to 6 milligrams per kilogram of body weight, taken about 30 to 60 minutes before your workout. For a 150-pound person, that translates to roughly 200 to 400 milligrams, or about two regular cups of coffee.
You don’t necessarily need that much. Doses as low as 2 mg/kg (around 135 mg for a 150-pound person, roughly one strong cup of coffee) can provide a noticeable boost. Going above 9 mg/kg doesn’t improve performance further and tends to cause jitteriness, nausea, and a racing heart. More is not better here.
Work Out When Your Body Is Naturally Primed
Your body has a built-in energy peak. Core body temperature, reaction time, muscular strength, and aerobic capacity all reach their highest point in the late afternoon to early evening, typically between 4 and 7 PM. This is when your cardiovascular system is most efficient and your muscles are warmest and most pliable. Studies show that aerobic energy production is measurably higher in the afternoon compared to the morning.
That said, the best time to exercise is the time you’ll actually do it. If mornings are when you’re most consistent, a proper warm-up and a pre-workout snack can close much of the gap. But if you have flexibility in your schedule and you’re choosing between forcing a 6 AM session or going after work, your body’s physiology favors the later option.
Warm Up to “Turn On” Your Energy Systems
A dynamic warm-up does more than prevent injury. It physically increases blood flow and oxygen delivery to your muscles, which ramps up your body’s ability to produce energy. Higher muscle temperature accelerates the chemical reactions that convert stored fuel into usable power. Five to ten minutes of light movement, such as brisk walking, leg swings, arm circles, or bodyweight squats, is enough to shift your body from rest mode into exercise mode.
Skipping a warm-up means your muscles spend the first several minutes of your workout operating inefficiently, which is one reason the beginning of a session often feels hardest. That sluggish feeling isn’t necessarily low energy. It’s cold muscles trying to catch up.
Play Music in the Right Tempo Range
Music genuinely reduces how hard exercise feels. In one study, listening to medium-tempo music (115 to 120 BPM) lowered perceived exertion from about 12 out of 20 to 10.5, a meaningful difference that can be the gap between quitting early and finishing your workout. Songs in the 115 to 145 BPM range tend to work best, matching the natural cadence of most cardio activities. Think upbeat pop, electronic, or hip-hop. Building a playlist at the right tempo is one of the easiest, most underrated ways to make a workout feel more doable.
Rule Out Low Iron
If you eat well, sleep enough, hydrate, and still feel exhausted during exercise, low iron stores may be the cause. You don’t have to be anemic for iron to be a problem. A condition called iron deficiency without anemia occurs when ferritin (your body’s stored iron) drops below 30 ng/mL while your red blood cell counts remain normal. Standard blood tests often miss this because they check hemoglobin but not ferritin unless you specifically request it.
Symptoms include persistent fatigue, poor concentration, and exercise that feels disproportionately hard for your fitness level. This is especially common in women, endurance athletes, and people who don’t eat much red meat. Studies show clear physical improvements in athletes whose ferritin levels were below 30 ng/mL once they began supplementing. If this sounds like you, ask for a ferritin test specifically, not just a standard blood count.
Recognize When Fatigue Means You Need Rest
Sometimes the answer to “how do I get energy to exercise” is that your body is telling you to recover. Overtraining creates a distinctive kind of exhaustion that no amount of caffeine or carbs will fix. When you’re overtrained, your nervous system becomes less adaptable, which shows up as a flattened heart rate response, persistent soreness, irritability, and workouts that feel harder despite not increasing in difficulty.
A useful rule of thumb: if you felt fine two weeks ago doing the same workout and now it feels brutal, and nothing else in your life has changed, you likely need more recovery days rather than more energy strategies. Taking two to three full rest days, or switching to very light activity like walking, often restores workout energy more effectively than pushing through.