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 The article’s core idea is that mental fatigue can make exercise feel significantly harder before you even begin, even if your actual physical fitness, strength, or endurance has not changed.

Key points:

• Your brain plays a major role in determining how difficult exercise feels.
• Stressful work, intense concentration, poor sleep, decision fatigue, emotional strain, or prolonged screen time can create mental fatigue.
• When mentally fatigued, people often perceive the same workout as requiring more effort, even though their muscles and cardiovascular capacity are essentially unchanged.
• This can lead to lower motivation, slower performance, and a greater desire to stop exercising sooner.
• The effect is largely about perceived exertion—how hard the exercise feels—rather than a sudden loss of physical ability.

Practical takeaways:

• Prioritize sleep and recovery.
• If you’re mentally drained, consider a lighter workout rather than skipping activity entirely.
• Warm-ups can help ease the transition from mental work to physical activity.
• Don’t assume a difficult-feeling workout means you’ve become less fit; your brain’s fatigue level may be influencing the experience.

In short, how rested and mentally fresh you are can strongly affect how hard exercise feels, even when your body is just as capable as usual.