When I started exercising regularly, before my workouts became a habitual part of my life, I used to get really anxious if I missed one.
I felt like all the work would be undone; that I would lose the fitness and strength I'd gained if I took my foot off the pedal.
The other day at the gym, I noticed a message on the wall. "One meal won't make you unhealthy," it said, "just like one workout won't make you healthy."
How true those statements are.
Now I know - having built some strength and fitness over the years - that I won't suddenly get soft and weak if I can't get to the gym once or twice.
Missing a workout or two won't kill me, and it might even be good, giving my muscles a chance to rest and recover.
If I miss five workouts though, I'll definitely feel it when I get back. And if I were to miss 10, I think I'd notice a difference in my body.
And so it is with healthy eating.
One meal at a raw vegan cafe is not going to make up for a week of junk food and minimal veges.
A green smoothie in the morning is not going to keep you healthy if you're skipping lunch and having a big, heavy meal at night.
As nutritionists are fond of saying, it's what we do most of the time that makes the difference, not what we do sometimes.
If we divide our week into eating opportunities - don't laugh, as a foodie I often think like this. When's my next chance to eat something delicious? - we have 21 chances to boost our health with nourishing food.
Including snacks, there are another seven to 14 smaller opportunities to get something good in.
Not every one of those meals and snacks has to be five-star, nutritionist-tick-of-approval perfection. But it is probably going to be better for us if a good number of them are.
It's going to keep us feeling better and if we have particular goals - weight loss, for example - sticking to the healthier side of the ledger is going to help get there faster. But we shouldn't forget that one meal isn't going to make us unhealthy, either.
Some popular diets promote the idea of "cheat days" - a day in the week when you go "off" the diet and eat whatever rubbish you like. This is crazy, encouraging a warped relationship with food and a binge-purge mentality that is far from healthy.
Thinking of eating any food as "cheating" frames food as good and bad and is emotionally fraught.
Food is just food.
Healthy eating is a practice.
With that in mind, it's important to look up from the minutiae at the big picture.
If that picture contains loads of plant foods and not too much highly processed foods, in sensible combinations, then the odd meal that's less than ideal shouldn't cause a panic.