One Rule to Drop Kick “All or Nothing” Thinking in Exercise

Find your gray area for lasting fitness success

By Kelan Ern
​Updated: 03/03/2025

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This week someone online asked:

How do you handle ‘black and white thinking’?

This person shared the urge to stick to a nutrition routine perfectly… get in 10k steps… and work out every day. And if they slipped up and ate cookies or didn’t go to the gym they would feel like they failed.

Here’s one way to break-out of all-or-nothing thinking:

The 80% rule

While many fitness pros and fitness bros have talked about this concept, it deserves a little unpacking.

Notice this is not the 90% rule (or 95%). If you want to get extremely lean… look like Christian Bale in The Machinist… or compete in a bodybuilding competition, you might have to raise your standards to that level (maybe even higher).

But for most people they don’t need to.

This is about staying on track 80% of the time. That means if you have 21 meals in a week, four of those meals can be ‘cheat meals’ (within reason).

For me, two of these cheat meals tend to be on Friday night (my fiancé calls it, Fun Food Friday) and Saturday night. And usually it consists of pizza (cauliflower crust or chicken bacon ranch) or occasionally a burrito or sushi dinner. Then during the week I stick to a heavy greens and lean protein routine, which keeps me feeling light, energized and helps me stay focused on my work (not distracted by deciding what to eat).

You can apply the 80% to workouts too.

If you have five workouts in a week, you could skip one and still be on track. This buffer allows you to have flexibility because life is going to happen.

It could be coming down with the flu (or in my case a cold that turned into sinus infection). Or it could be seafood dinner night… potluck at work… or having a ‘wild hair’ and picking up a burger from the local restaurant.

And any one of those could derail your whole week if you absolutely, have-to, stick-to-the-plan at- all-costs or else you’ve failed. Instead realize this is part of the buffer that you put in place to allow yourself not to have to be perfect all the time.

Because in the end, your fitness routine is a hypothesis.

It’s a guess.

It’s an attempt at creating a map to accomplish your fitness goals… but chances are it will take many, many iterations to make it work for you. And to honor that process one of the smartest things you can do is put in buffers that allow you to slip, stumble and fail from time to time.

That way you can get up stronger (without the guilt) and use those lessons to make your plan even more effective.

Kelan Ern
Fitness Coach

P.S. For more ideas to transform your health and fitness, check out a free issue of Mind-Body Breakthroughs. Each monthly issue features one of the fittest people on the planet and their tips, strategies and mindsets for helping you breakthrough to the next level.