Health is really a holistic thing, it is not about just doing one thing. You, all of you, body, soul and mind all need to be going towards a common goal of health.
For most people the place they tend to start is the idea of getting healthy is working out hard and getting skinny. Big thing right there. SKINNY DOES NOT EQUAL HEALTH. I want that permanently etched in to your brain. Yes healthy people tend to be leaner and their body portions tend to proper. Though just because some is skinny does not mean they are healthy. The same can go the other way, just because you aren't skinny doesn't mean you aren't healthy. We all have different shaped bodies, there is no mold everyone is a bit different.
Your Body: You need movement it is a need without you will waste away. You know the saying " use it or lose it". This couldn't be more true. Stretching, lifting walking moving your body in many different ways is best for your health. Also getting checked by people who special in bodily health ( massage therapists & Chiropractors) is really good for the things you can't do yourself.
Your Mind: You thoughts even fleeting ones can shape you. If you have regular toxic thoughts in your mind, the toxicity will be in your life. You need to be thinking healthy to move towards being being healthy. Are you think that it is hard and something you could never do? Then it will be hard and something you will never do! Your thoughts are amazingly powerful, let them have the power to help you
Your Soul: Whether you believe in any sort of divinity or not is irrelevant. You have something about you that controls and centers you. Many people work on focus with yoga, meditation and prayer. yours needs to be positive and believe in you. Before others can believe that you will make the change you have to believe that you will make the change.
Think about you as a whole not just the parts that make you whole!