8 Possible Reasons Your Workouts Feel Harder Than They Should

8 Possible Reasons Your Workouts Feel Harder Than They Should

(Last Updated On: April 14, 2019)

exercise motivation

Have you noticed how some days a workout feels easy while other days even a little movement feels tough? Ebbs and flow in motivation and exercise performance happen naturally based on your energy level, mood, stress level, and how fueled you are before your workout. No one always feels 100% like working out, but if you find that workouts frequently feel hard or excessively tiring, here are some possible causes.

Lack of Motivation: Your Iron Level is Low

If you repeatedly feel spent after a workout or have a hard time garnering the energy to work out in the first place, check your iron level. Low iron stores or full-blown iron deficiency anemia is relatively common in women before menopause, especially women who eat a vegetarian or vegan diet or have heavy periods. If iron deficiency anemia is causing your workout motivation to suffer, you may have reduced exercise intolerance, lightheadedness, and feel short of breath when you climb a flight of stairs. But, in milder cases, the symptoms can be subtle. You might only feel more fatigued than usual and have less motivation to work out. A simple blood test can tell you if iron deficiency is making your workouts feel harder.

Lack of Motivation: You’re Not Hydrating Enough

Dehydration is another common cause of fatigue. Studies show mild dehydration of only 2% can impact a workout and how you feel doing it. When you’re low on fluid, your heart has to pump faster to deliver blood and oxygen to cells and tissues. The extra work your heart has to do when you’re dehydrated makes exertion feel harder. Research shows dehydration of only 2.5% reduces high-intensity exercise performance by 45%.

How much fluid do you need to optimize your workouts? Baseline, you need between 0.5 and 1 ounce of water for each pound you weigh every day. You can monitor for dehydration by noting the color of your urine. If you’re hydrated, it should be pale in color. Anything darker than pale yellow means you’re not drinking enough!  Dehydration is especially risky when you’re exercising in a hot environment. When you don’t drink enough fluid, your body can’t deliver as much fluid to the surface of the skin to release heat.

Lack of Motivation: Medications

Medications that cause drowsiness, including some antihistamines used to treat allergies, can zap your energy and make a workout feel harder. Any med that causes you to feel sleepy can make it harder to shift into exercise mode. But meds that directly induce sleepiness aren’t the only culprits. Certain medications that treat high blood pressure and heart problems can too. One example is beta-blockers. These medications slow your resting heart rate and make it harder to reach your target heart rate during exercise too.

Lack of Motivation: You’re Choosing the Wrong Carbs

You might grab a carby snack before a workout in hopes it’ll fuel up your workout. But, the wrong kind of carbs can send your blood sugar crashing during a workout. In fact, this is one of the most common causes of workout fatigue. You can compensate for diet-induced fatigue by changing the composition of your diet. Choose carbs that have enough fiber to moderate the blood sugar response and keep your glucose level steady during your workout. Make sure you’re consuming enough protein too. A good rule of thumb is to fuel up with 2 to 3 grams of healthy carbs per gram of protein 2 hours before a workout.

Lack of Motivation: Your Thyroid is Underactive

Your thyroid gland is the master regulator of your metabolism. If it’s under-active, your metabolic rate drops and you fatigue more easily. Other symptoms of hypothyroidism, an underactive thyroid, include:


·        Decreased heart rate

·        Fatigue

·        Dry, flaky skin

·        Feeling cold all the time

·        Constipation

·        Weight gain

·        Muscle weakness

·        High blood cholesterol

·        Pain, stiffness or swelling in your joints

·        Menstrual irregularities

·        Thinning hair


If you have any of these symptoms, ask your physician to check your thyroid gland. One in seven women will experience thyroid problems in their lifetime. The most common cause is an autoimmune form of thyroid disease called Hashimoto’s thyroiditis.

Lack of Sleep

This sounds like an obvious one, but many people aren’t aware of how little sleep they actually get. Sleep quality counts too. You may think you’re getting 7 or more hours of sleep, but if you wake up frequently throughout the night or toss and turn, you may still be exhausted. Lack of sleep harms exercise performance in several ways. Research shows it decreases the amount of stored glycogen in muscles and if it’s ongoing can lead to muscle breakdown through increased release of cortisol. Plus, it’s harder to focus and stay motivated when you’re tired. Most of us need a minimum of 7 hours of quality sleep to feel and function our best and to maximize our workouts.

You’ve Taken Too Long of a Break from Exercise

If you take a long break from exercise, expect to feel slower when you return. You can notice a slight decline in aerobic capacity after only 2 weeks of not exercising. Even a slight decrease in stamina makes a workout, particularly cardiovascular exercise, more challenging. We need breaks from exercise now and then but take a day or two off each week and don’t over-train so you can avoid burnout!

You’re Bored

If you’re doing the same exercises over and over, your workout may feel harder because you’re bored. It’s not that you lack energy, you just don’t feel like doing the same old workout yet again. Add variety to your routine. Shorten your workouts and make them more intense by adding high-intensity interval training. Mix things up by doing circuit workouts. Vary the exercises you include in your circuits. If you’ve never tried yoga, give it a go! Add some new workout music or lace up a new pair of sneakers. Little things like this give you a new outlook and fresh motivation. Also, make sure you’re keeping an exercise journal, so you can see how you’re progressing. That’s motivating too!

The Temperature Isn’t Ideal

Exercise places more stress on your body when you exercise in a hot or humid environment. Your heart has to work harder to deliver blood to the skin to release excess heat. Plus, a stuffy, sticky environment makes exercise psychologically more daunting. It also increases the perception of how hard you’re working. Add a fan or two to your workout area to make your workouts feel more pleasant.



·        Mayo Clinic. “Beta blockers: How do they affect exercise?”

·        WomensHealth.gov. “Thyroid Disease”

·        Human Kinetics. “Dehydration and Its Effects on Performance”

·        National Sleep Foundation. “Sleep, Athletic Performance, and Recovery”


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