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A chemical explanation for why we give up on tough tasks

Several people ask me to give mantras for motivation.

They start some work. But very soon they lose all interest in it and abandon it. Why? Lack of motivation?

Strangely, I never find myself in such situations. So my motivation is permanent!

Motivation is the internal or external driving force that initiates, guides, and maintains goal-oriented behaviour. It explains why people start, continue, or stop an activity at any given time.

Types of Motivation

Intrinsic Motivation: Stems from internal factors like personal enjoyment, curiosity, or a sense of identity and purpose.

Extrinsic Motivation: Driven by external rewards, such as money, grades, praise, or the desire to avoid punishment.

Family or Social Motivation: Pursuing goals—such as going to a job you dislike—to support or protect loved ones.

Why do some people lack this motivation?

Science now has a chemical explanation for why we give up on tough tasks

When we engage our brains in a mentally taxing task, we eventually reach a point where we hit a wall or run on empty. Even when the rewards of finishing are obvious, we often find ourselves simply stopping. Exactly why this happens has long remained a mystery. We can easily point to tiredness or lack of motivation, but what is driving this disengagement at a biological level?
That is precisely what a team of scientists set out to answer in experiments involving 31 healthy volunteers.

Each participant took part in a demanding 20-minute memory test on two separate days. During one session, they received electrical stimulation designed to increase activity in part of their prefrontal cortex. During the other, they received a fake version that delivered a brief initial tingle to make it feel like the real thing.

The test was designed to induce mental fatigue. To measure its effects, researchers asked participants, both before and after the test, whether they would be willing to complete additional memory tasks. They could choose between easier ones for smaller cash rewards and harder ones for more money.

The research team also measured brain chemistry before and after the tests using magnetic resonance spectroscopy. They were paying particular attention to glutamate because previous research has linked this brain chemical to mental exhaustion.

The scans confirmed a clear pattern, as the research team details in a paper published in the Proceedings of the National Academy of Sciences.

Active stimulation increased the excitability of the dorsolateral prefrontal cortex (DLPFC). This was associated with significantly higher glutamate levels after the test compared to the control. While this increased brain activity initially boosted memory task performance, there was a downside. Volunteers became less likely to choose high-effort tasks after the test, even when this hard work paid more.

"Yet, this performance benefit from enhanced DLPFC excitability came at the cost of a subsequently reduced willingness to select high-effort options, indicating increased motivational fatigue," wrote the scientists in their research paper.

The study suggests a possible biochemical cause for the reduced motivation associated with mental fatigue. If this turns out to be a driving mechanism, it could form the basis of new medical interventions when exhaustion becomes severe or chronic.

Prefrontal glutamatergic metabolism may thus serve as a potential biomarker as well as treatment target for pathological fatigue.

Hongmei Xia et al., A causal account of the neural origins of mental fatigue, Proceedings of the National Academy of Sciences (2026). DOI: 10.1073/pnas.2534136123

This paper brings in more questions.

If your biochemistry is not favourable for motivation, can a motivational speech or quote or write up change the situation?

The answer is

a motivational speech, quote, or write-up can change your biochemistry, but its effects are "usually temporary". While we often think of motivation as a purely mental state, it is deeply tied to neurotransmitters like dopamine, serotonin, and cortisol.

External inputs can act as a catalyst to shift these chemicals, though the extent of the change depends on the underlying cause of your low motivation.

How this interaction works

1. The Biochemical shift from external motivation

When you read an inspiring quote or listen to a powerful speech, your brain undergoes immediate cognitive and chemical changes:

The Dopamine spike: A compelling message or a resonant goal can trigger the anticipation of a reward. This causes a temporary release of dopamine, the molecule responsible for drive, focus, and the desire to take action.

Cortisol and Adrenaline regulation: An energizing speech can activate a mild, positive stress response (eustress), raising adrenaline to pull you out of a sluggish state. Conversely, a comforting or reassuring write-up can lower high cortisol (stress) levels that might be causing motivational paralysis.

Neuroplasticity: Consistently exposing yourself to empowering narratives can gradually reshape your cognitive framing, making it easier for your brain to access motivated states over time.

2. The limitations of "words" on Biology

If your unfavourable biochemistry is caused by deeper physical or physiological factors, words alone will act as a temporary bandage rather than a cure. A motivational speech cannot instantly fix:

Clinical deficiencies: Severe depletion of dopamine or serotonin (often seen in clinical depression or ADHD).

Nutritional and sleep deficiencies: High exhaustion, lack of sleep, or micronutrient deficiencies (like Vitamin D, B12, or Iron).

Hormonal imbalances: Issues with thyroid function or chronic burnout that keep cortisol permanently elevated.

In these states, a quote might give you a 10-minute burst of energy, but the brain will quickly return to its baseline deficit because the underlying biological machinery lacks the raw materials to sustain it.

3. Turning "words" into lasting chemistry

To make an external motivational boost stick, you have to use that brief window of chemical arousal to change your physical state.

Action should precede motivation: Do not wait for the chemistry to feel perfect. Use the tiny spike of energy from a speech to do five minutes of a task before it recedes. The act of achieving even a micro-goal triggers a natural feedback loop, releasing more dopamine and sustaining the motivation organically.

Pair with physical movement: If you listen to a motivational speech while sitting in a dark room, the effect is muted. Listen to it while walking, doing light stretching, or changing your posture. Physical movement alters blood flow and hormones, reinforcing the mental shift.

Constant high-grade rewarding: Try to make the high grade rewards permanent to boost more favourable chemical supply by constantly upgrading the targets and goals and achieving them more and more as success makes you an achievement addict!

Several students tell me that my work inspires them. Then I ask them why don't they get really inspired to do the work.

The answer is - they are unable to change motivational words or work into permanent brain chemistry to sustain that inspiration.

A chemical explanation for why we give up on tough tasks

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