How do I make eating healthy, a lifestyle?

I’ve eaten unhealthy all my life but now it’s time to turn my life around. How do I go about eating healthy for breakfast , lunch and dinner. How many servings of vegetables and fruits shall I eat. Could I substitiute fruit juice for fruit? What are some healthy alternatives for snacks? Food really isn’t an option I here at college and they have all sorts of food options. Even if the main course is unhealthy there still the salad bar and sandwich bar and fruit. So can ya help?