I'd be buggered if I didn't plan and prepare.
Every week, I make sure I have the week's training schedule laid out in advance. Yes, there is room for flexibility and shuffling sessions about if it needs to happen due to work and real life not being 100% predictable, but the week has a shape and set sessions from coachJez's programme (or mine if there isn't one from Jez). Without a plan and a schedule in place, my training would be directionless in general (which, by itself, is an enormous long term problem) and on a day-to-day basis I'd have no idea what to pack in my sports kit bag.
The same goes for food. Breakfasts are relatively easy and cookie-cutter (no, I don't have cookies for breakfast!). Lunches and daytime snacks generally have to be sorted in batches in advance; making lunch and snacks every morning for that day at work is a heck of a drag and relying on that energy being there every day just doesn't work. So, every couple of days I make lunch base of all the vegetables and fruit and the protein gets added on the day. I have a couple of snacks in the fridge at work and pots of portioned out nuts and a pile of fruit alongside a big plastic box of other safe snacks like wholegrain and seed breads, mixed nuts and seeds, cereal bars etc. And dinners are planned on a daily basis, to a rough weekly cycle to cover getting in some oily fish, red meat, white meat and eggs. But again, if left to when I get home from work to think about it there's a requirement for a big surge of emotional energy required to think it through and sort it out, when I'm just tired and hungry and likely to just go for whatever's easiest at the time. There's weekend batch cooking that covers a couple of meals a week and the rest is quick to cook from scratch (usually 30 minutes or less, e.g. omelettes, frittata, salmon fillets with couscous & veg, steak and veg, sausages and root veg mash).
Without that planning and preparation I'd fall by the wayside; I'd train less, I'd eat badly more, I'd get stressed out by it all more often, I'd make much less progress. There's so much energy needed to do the training and the showering and the working and the eating and the cat feeding and the recycling and the commuting and the washing and the sleeping and the putting the washing away and the shopping, any savings that can be made by bundling planning and preparation up and doing things when the energy and inclination is there in advance of when they're actually needed are well worth having.
It sounds a bit bloodless and mechanical, but it's not. There is always room for spontaneity, it's just not compulsory to get through every day. Spontaneity is hard to do all of the time. Planning and preparation is what successful people do to be successful.