Written by: Jackie Brennan, Executive Contributor
Executive Contributors at Brainz Magazine are handpicked and invited to contribute because of their knowledge and valuable insight within their area of expertise.

I'm sure we've all been there. The alarm rudely awakens you and you drag yourself out of bed, even though your body wants more sleep.

You battle with traffic or maybe your internet connection just to get to work.
You hold back when a colleague annoys you or you’re put on ‘hold’ for ‘a second’ that turns into 10 minutes.
You sit through a boring presentation with an engaged expression on your face.
You postpone going to the bathroom telling yourself 'I'll just finish this first'.
You force yourself to have the green salad rather than the chips you’d much prefer.
You drag yourself to the gym and stay until you’ve finished your full workout.
You collapse at home with a beer or glass of wine, elbow-deep in a bag of crisps even though you resolved to 'be good'.
Now, before you sigh and think, "Why am I like this?" consider this:
It's not just about mental strength – it’s intricately tied to your physiology and the science backs this up.
Beyond mere determination
It's a popular refrain – just muster up enough determination, and you can resist any temptation.
We've been taught that willpower is like a muscle, and if you simply 'train' it often enough, its resilience will grow.
Yet, if this were entirely true, wouldn't we all have ironclad discipline after a few resolute stands? The reality isn't so simple.
Relying solely on determination overlooks a vast array of physiological processes that drive our choices.
Practice makes perfect
Extending the muscle analogy, there’s a notion that frequently resisting temptations amplifies your resolve.
Yet, imagine continuously pushing yourself at the gym without rest – exhaustion will set in.
Similarly, pushing your willpower without understanding its workings can result in predictable setbacks.
And here’s where the science weighs in…
The finite nature of willpower
In the 1990s psychologist Roy Baumeister presented the ‘ego depletion’ theory, likening willpower to a phone battery.
Everything from resisting that chocolate biscuit to holding back a frustrated sigh drains this battery.
He called these tiny willpower power-outs ‘self-regulatory units’ (SRUs). Every decision, emotion control or treatment denial consumes SRUs. And just like any battery, there’s a limited charge.
Spend them all? Your willpower's out for the day, explaining why most of us are raiding the fridge come evening!
The two pillars of SRU replenishment
1. Glucose: The brain's preferred energy
Your brain is an energy guzzler, relying heavily on glucose, consuming nearly 20% of the body's energy.
So when you're determining whether to take another biscuit, making decisions or suppressing an emotion, your brain is voraciously burning glucose.
As blood sugar drops, the brain struggles, making impulse control harder. It's not merely a sugar craving, it's the brain's plea for more energy.
2. Sleep: Willpower’s silent ally
We’re all familiar with the foggy feeling of a sleep-deprived brain. But beyond just feeling groggy, lack of sleep SRU reserves.
Scrimp on sleep, and you're practically asking your willpower to take the day off.
A well-rested brain is better at managing emotions, making sound decisions, and resisting impulsive urges.
Sleeping might well be one of the simplest (and most enjoyable) ways to enhance willpower.
In summary
Before berating yourself over an evening indulgence, shopping spree or momentary lapse in judgment, remember that willpower isn't just about determination. It's deeply rooted in your biology.
To truly master it, you must understand it.
So stay tuned for the next exploration into elusive force.
In the meantime – keep your blood sugar levels up and get some good-quality sleep!
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Jackie Brennan, Executive Contributor Brainz Magazine
Jackie Brennan, the Construction Wellbeing Catalyst, is an international speaker, sought after coach, trainer, CEO and Founder of Construction Wellbeing. After working in construction for 39 years, from the ground up to the board table, Jackie knows what it takes to build a construction company that really thrives. She also knows where the gaps are. Jackie literally turned her life upside down after she realised that whilst she loved her job, she also wanted something more from her work. Instead of returning to a corporate job she decided to take on a new purpose and direction by sharing a different perspective on mental health. Today, through speaking and coaching, she challenges current thinking and se