Prior planning prevents piss poor performance - 6 Ps - essential I think!
Not everyone can plan a whole week in advance but even planning day by day can make such a big difference.
Not everyone likes to plan, they like to see what they want at each meal time, if this is the case then it's best to have plenty of good food in so you can have a healthy meal.
When I did not used to plan at lunch times it's what do you want? I don't know? Oh let's go out for lunch which leads to unhealthy meals, luckily I am now much stronger so make good choices eating out. At 6pm it can be the same, what to have for tea? It's Late, you can't decide do take away is ordered. Having good food in or planning ahead can make sure these situations are avoided.