I think you probably know the answer to this question: sensible eating and drinking and exercise on a daily basis, some of it aerobic. 150 hours of moderate aerobic exercise a week, don't smoke, eat more fibre, avoid too much salt - this is vital -, eat fish especially oily fish, keep to your 5 a day veg and fruit.
You have to build this into your daily regime and not let the pressure of work persuade you that you have no time to choose your food or exercise.