1) I eat super clean. No junk food, lots of non-processed meat, veggies, fruits, nuts and seeds, fish, yogurt, etc. There's a lot that could be said here but I'll keep it short. Everything you need for a breakfast of champions full of vitamins and nutrients.
2) Exercise 5 or 6 days a week. Find an activity you enjoy so it's easier to keep the habit.
3) I meditate every day. This can be replaced with yoga or something similar you enjoy.
4) 8 hours of sleep every day. Going to sleep and waking up at the same time consistently is a huge help with developing and keeping this habit.
5) [This one's less critical than the others but still somewhat important]. I'm careful about what influences I'm taking in e.g. listening to uplifting music vs something dark and depressing. What tv shows I'm watching, who I'm hanging out with, etc etc. Build a kickass life with friends and hobbies you really enjoy.
This is just what's worked for me personally but I think research generally backs them up. The details are, of course, a bit contested, like how much meat you should eat.
Like any habit, it'll be hard to get into the routine but it'll definitely get easier -- your palate will adjust to eating healthier, you'll start to enjoy working out. Plus each of these things helps the others -- e.g. over time, exercising improves quality of sleep. Pretty soon, though, you'll see results that make it much easier to keep the routines and develop them further.
The results are pretty phenomenal. I'm much healthier and happier, more optimistic, relaxed, motivated, and productive, and have more energy and focus. You're gonna love the way you feel, I guarantee it haha. Hope some of that helps :)