If you’ve been following along with the Cups, you already know the basics: each Cup represents a need. Safety. Connection. Freedom. Mastery. Fun.

This episode is about a piece of the framework that makes everything else make sense.

The Will to Fill.

It’s the part of the Cup you don’t always notice… until you really notice it.

Chris uses a funny little analogy in the Cupify This podcast. Imagine you order a pint of beer and the bartender only fills it three-quarters full.

Technically, it’s still a glass with beer in it.

But to you, the person who ordered a full pint, it’s a short pour. The empty part matters because it’s the part you expected to be filled.

That’s the idea Chris is playing with.

A “need” only exists when something is missing. If it’s already met, you don’t experience it as a need anymore. You’re not walking around thinking, “I need air.” You just breathe. You don’t sit there thinking, “I need connection,” when you’ve had a good day with your people. You just feel… fine.

Needs are felt most clearly through what’s lacking.

In Phoenix Cups language, the Will to Fill is the empty part of the Cup.

It’s the pull towards filling it. The urge. The drive. The “I’ve got to do something about this” feeling.

And it matters because this is where motivation comes from. The Will to Fill is what pushes behaviour into motion.

Without it, you wouldn’t get out of bed. You wouldn’t eat. You wouldn’t reach out to a friend. You wouldn’t build a life. You’d have no reason to do anything, because there’d be nothing pulling you towards meeting your needs.

That’s why, in the episode, Chris calls it an “active nothingness”. A strange phrase, but it points to something true: the empty space isn’t passive. It does things. It creates movement.

Talking about “lack” and “emptiness” can sound dark if you sit with it the wrong way. Sandi makes an important point in the podcast: the Will to Fill isn’t good or bad. It’s neutral. It’s just the motivator.

It can feel uncomfortable. It can also be useful.

You can even think about it as capacity - the space you still have to fill. Potential. Opportunity.

If your Connection Cup is half full, you can read that as “I’m missing connection” and feel flat about it. Or you can read it as, “I’ve got room to fill, who do I want in my life right now?” and take action from a better place.

Same Cup. Same empty space. Different mindset.

This part is important. A lot of the time you’ll notice the Will to Fill in your dominant Cups, because those Cups are bigger. They take more to fill, and you feel the “gap” more often.

But the Will to Fill can also hijack your day through a Cup you don’t usually prioritise.

Sandi gives a great example: on a big conference day her dominant Mastery Cup is thriving - full, satisfied, ticking boxes. But she forgets to eat. Her Safety Cup might be much smaller overall, but when it drops low enough, it becomes urgent. That’s when the body and brain steps in and says, “Enough. Food. Rest. Stop.”

So yes, Cup size matters. But emptiness matters too. When any Cup gets low enough, your Will to Fill will pull you towards it, whether it’s your biggest Cup or your smallest.

There’s another layer here. When the empty part of a Cup gets big enough, it can trigger a stress response.

Fight. Flight. Freeze.

You stop thinking clearly. You can’t focus on anything else. Your system narrows in on the unmet need and demands attention.

That reaction is your nervous system stepping in to keep you safe.

And it’s also why people can look “dramatic” when a Cup is emptying. But they’re not performing, it's their brain trying to protect them and solve a real problem, even if it comes out messy.

If you want to make this practical, try this check-in:

Ask: “Which Cup is pulling at me today?”

Then ask: “Is it asking for a small top-up… or is it empty enough that I need to stop and make a plan?”

Even naming it changes things. It takes you out of confusion and into clarity.

This blog is the gist version. In the full episode, Chris and Sandi unpack the Will to Fill with more examples, more back-and-forth, and the bigger picture of how this concept sits inside the whole Phoenix Cups framework.

Next up is the companion concept: the Skill to Fill - the part that explains why some people stay stuck in the same patterns, and others learn to meet the same needs in healthier, steadier ways.

Author: Sandi Phoenix