It's easy enough to eat well when life is ticking along nicely. When we're in our regular routines, when things are going well, when we feel in control.
But when life throws us something tricky or challenging, it's easy for good habits to be derailed.
Many Kiwis have experienced this in the past week, since the earthquakes shook us awake.
The people directly affected have had their worlds turned upside down.
It's also had an effect on those who have already been through the trauma of the Christchurch quakes, for whom something like this brings back a lot of stressful, painful memories.
The everyday stresses of work, family, relationships and money are common to us all.
And then there are upheavals that tip us all off balance. Death, illness, job loss, breakups.
Even happy events like the birth of a child, a new job or a new house can cause stress that throws off our routines and makes what was once habit, now hard.
Healthy eating feels like the last thing we can be bothered about.
And yet we know eating well and generally looking after ourselves is a very good way to counter stress.
The worse we eat and the more we rely on alcohol and caffeine to get us through times of stress, the worse we are likely to feel.
Our bodies can cope with some stress - but we aren't designed to cope with stress all day, every day.
There are various hormonal changes that happen in response to stress, including increases in adrenalin and cortisol.
When the body has to constantly churn out large amounts of these stress hormones it has flow-on effects on overall health.
This has been demonstrated in the people of Christchurch.
A 2014 survey of Cantabrians found one in four respondents had become reliant on overeating to deal with stress.
One in five relied on alcohol or coffee consumption to cope. And four in five said they were not as fit as they would like to be.
It's all very well saying "eat a healthy diet" to counter stress, but that's probably not going to cut it when life feels like it's falling down around our ears.
When you can't get back into your house and have no power or phone, a healthy salad is low on the priority list.
In that case, eating whatever is available and sustaining is likely the only option, at least temporarily.
But for those of us dealing with other more everyday stresses, we would do well to remember that stress does make it hard to keep good habits going.
We shouldn't be too hard on ourselves; self-compassion is important.
But also: giving priority and time to exercise and eating well is not being selfish.
It's important self-care, and it can make a big difference to how well we cope with the next challenge that comes along.