It can be said that the rapid consumption of energy is one of the reasons that my working day is so short. But I go to bed early :)
In general, I read Wikipedia, I study. Thank you!
Ahh. In that case, there's some food items you can use to both accelerate your mine delving and keep your energy going. First off, Spring Onions show up south of your farm, on the other side of the river, and are nearly worthless to sell so you might as well just eat them. Those appear for the first couple of weeks. After the Spring Dance, Salmonberry season starts. Shaking berry bushes will net a berry, or two if you have a Foraging skill of 4 or greater. Foraging 8 seems extremely unlikely, but that's the break-point for 3 berries, and if you eat some stat food to raise your effective Foraging skill to 12, you net 4 per bush. They sell for very little so again you are free to use them to fuel your mine diving and general energy needs. On a good week, I can get a few hundred berries, which will last quite some time.
Once you are more established, I find Cheese, particularly gold-star Cheese from pressing Large Milk to be a particularly amazing health and energy restoring item. Given cows produce milk daily, and once at max hearts they produce large milk regularly, it's a really good way to have a consistent food source. Cheese also makes a generally decent gifting item for most townsfolk (with some notable exceptions) and sells pretty well too, so you have options on what to do with your cheese if you choose to own cows.
Once you obtain the recipe, you can also use Cheese to combine with Peppers in a kitchen (needs at least one house upgrade) to make Pepper Poppers, which grants a Speed bonus that stacks with Coffee's speed bonus.