Just eat healthy and get some exercise 4-5 days a week.
Most of the time I drink water, and if we're moving outside of water its just coffee, tea, and smoothies.
Your meals should consist of solid, but healthy food.
Vegetables are your friend, as are lean cuts of meat, grains like rice and quinoa, and fruit.
This is all it takes, just be consistent, and get a partner who will keep you accountable.
Biking, jogging, daily pushes, sit ups, lunges and crunches are all ways to get in some exercise.
Get a gym membership, it may help.