If you break your wrist or your knee, it screws up your life immediately, and likely does some damage to you for the long-term. You'll probably have somewhat lower peak athletic capacity, and have to be more cautious around the once-damaged area.
That's obvious in the case of a large trauma, but less obvious are the everyday actions we take that have ripple effects throughout our lives.
Taking the time to clear the decks of distractions, clean up and either finish or officially cancel old projects, making incremental improvements to diet, learning minor time-saving techniques that add up (keyboard shortcuts, typing faster, etc)... the gains to these are largely invisible, but they have a positive ripple effect going into the future.
If you have a great idea on Tuesday, you might not attribute it to being better rested and sharper-thinking because of dietary and sleep hygiene changes you made a few weeks before. But indeed, the ideas that are most useful to us are the ones right at the edge of our problemsolving ability.
The flipside is the debt you build up from bad choices in passing. Since quitting fried and microwaved food a while back, I noticed better energy levels. How many times have I been able to avoid a stupid argument or deadlock because I was slightly healthier and clearer-thinking? I've been 100% consistent with my fitness regime. How much of that is attributable to better sleep? Or, phrase differently -- how many more arguments would I have had, and how much more often would my positive habits have broken down if I'd been eating fried foods and sleeping more poorly?