Being an entrepreneur is a multi-faceted endeavor, in addition to needing to be willing to work hard, you've got to be preparing your mind and body to do that work well ahead of time. Here are a few habits besides "wake up earlier" and "eat healthy" that you can put to practical use.
Don't Go It Alone With Your Organization
People like to think that they will keep themselves perfectly in line with just a bit of note taking here, a bit of list making there, but the reality is that most people practicing this organizational 'method' end up with sticky notes everywhere and sheets of paper that tend to disappear before you need them again. Instead, consider using a web app like Trello or Evernote to keep everything organized and in sync.
Start The Night Before
When you are organizing your (now digital) to-do and deadline lists, it's a good idea to get them set in place the night before. This has a couple of benefits. One, is that it's easy to let this drag out when starting your work day, but you'll likely want to be concise about it if you are cutting into your evening personal or even sleep time. Plus, if sleep is an issue for you, you can ease anxiety about the next day's happenings by having them planned out in advance. Two birds, one stone.
Eat More Regularly
No one else needs to tell you what to eat, that's up to you, but many of us do need to be reminded when to eat, as it can become too easy to sit and work away for hours on end without so much as a snack. Much of the time we begin to feel tired, especially during an afternoon slump, our bodies are actually dehydrated and/or in need of some caloric energy! Make sure you're taking this into account in your own schedule, and try and have a hard cutoff so you don't keep doing 'one more thing' until your mealtime has long passed.
Find a Break Schedule That Makes Sense
Focusing alone on one task for extended periods of time can be tedious and tiring, so make sure you're doing right by yourself and establishing a schedule that gives you breaks. For some, this may mean you simply work for an hour, take a 15 minute break, etc. For others, it might get more complex. Some people swear by a quicker pace in which they focus on something intently for 25 minutes, then completely disconnect for 5.
As with all of these habits, this last one is less about what exactly 'works' but more what works for you. This can mean making lots of little tweaks for your own situation, but the end results will be the same - a healthier, more productive, less-stressed you.