The world is vast, complicated, unpredictable and subject to chaos, that is minor differences in the starting conditions of any situation rapidly causes vast variations in later outcomes. So how can you plan for a future situation when our current state is unknowable other than in a cursory sense, and subject to so many assumptions, interpretations and incomplete knowledge, that it can only be described as your best guess rather than any objective truth.
Economists laughably use numbers to try and predict the future, when the current state of an economy is not even known, and subject to constant revisions as more data comes in, and only ever approaches a level of confidence. Which means we know what happened today in about twelve months time, so the idea that we can say what is going to happen tomorrow when we only have a best guess at what happened today is approaching levels of absurdity that comedians never try to imitate. That is why you should never trust economists with a spreadsheet, as they have been blinded by the goddess of mathematics who promises precision in a world where everything affects everything else and numbers can not describe anything as complicated as a single human being.
At best we can predict tendencies and possibilities, however reality depends on the actions of over seven billion individual human beings, who have a horrible tendency to think for themselves and act in any immediate moment in their own best interests. People will game the system and it doesn't matter what the system is, the moment people become aware of the system, there is a motivation to act against it, if it results in a better outcome for yourself. In that way people act like fields, that is the electromagnetic type not the nice honest dirty type that are full of mud. We effect each other and how we behave, in a weak or strong way.
Whilst the idea of a field is simple enough for humans to understand, that is the strength of a field becomes stronger as you move towards its centre, in a proportional way, that is it doubles its strength every time you move half the distance towards the centre. The implications of this is so difficult in a mathematical sense that scientists cannot even predict how three different bodies and their associated fields will interact with each other, whilst humans can play pool which shows that feelings can be a better guide to the future than mathematical analysis.
And this is where human planning can have an advantage over strict logical analysis. As a species we seem to have a shortcut through chaos to see the likely outcomes of our action, and our minds points us towards what the problems are likely to be. Strangely the less we try to use our logical ego minds to decide on what we should be worrying and planning about, and instead let our quiet inner voice decide on what to spend our time on, the more prepared we seem to be for the odd and unexpected situation that we seem to encounter all the time.
So when your mind wants to prepare for the Zombie Apocalypse, feel free to let it despite the protests of the logical mind that is unlikely and a waste of time for a grown-up to spend their time on. It is a little like dreams they may hide their point behind a lot of weird images, however they do have a habit of being on the money. And if in your mental checklist of things to do before the apocalypse, there are useful things that could be done to prepare for an everyday boring kind of emergency, it is probably worth noting that it is something you should do anyway.
In the same way the mathematical probabilities of you being the same room as Taylor's swift or Brad Pitt is, let's be kind and say unlikely. There is no harm in daydreaming about them, imagining meeting them and what you would say, especially if you were to imagine the type of person who would be interesting to them, as this would act as motivation to move closer to being that type of person. As we've stated before being comes before doing and then having, when we decide to be a certain type of person we start doing the things that type of person would do, and before we know it we have the life of that person, we are literally become that person.
I'm going to assume that that person is a better version of yourself rather than worse, you can approach that better version in as smaller steps as you are comfortable with, though there is no limit on how big your steps can be, apart from what you personally can find credible. As the first step towards being a better version of yourself is visualising yourself as that person with the key proviso that it feels real to you, because if you don't believe it, it will not happen. Whilst that may seem like a limitation, it is only so when that limitation actually limits you, so in theory whilst there might be some limit to how much you can improve yourself, but as long as you are only taking small steps, you might rapidly find you walk past what were your previous limits. The key is adopting the mindset of already having something before the reality wave catches up to you and decides what you actually are.
Of course, there is plenty of small scale planning that is worth doing as well, having a list and flexible attitude is useful, as no plan survives contact with the enemy or even just real life, but knowing what your priority is for the day helps to make sure that you get at least that one thing done which moves you towards your goals or makes your life better. However figure out what those goals are in any structured or unstructured way that appeals to you, I find the question of what is your perfect day, very useful in this regard. Once you discover it, plan the first step, execute and repeat, and then get on with being presence in your life today and in this moment.