When we think about health, we tend to think mostly of physical health, and of the absence of impairment. It's perhaps more useful, however, to think of health as not just the absence of impairment, but also the presence of positive function, across the physical, intellectual, emotional, social, spiritual and environmental health dimensions. In fact, this is how the World Health Organisation defines health: "Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity" . The other important thing to recognise about health is that it's dynamic. The health you're born with is not the health you will have for the rest of your life, and the health you have today may not be the health you have tomorrow (eg illness, injury and heartbreak are all immediate damages to your health status). Here's another example of life events suddenly changing one's health status:
There are three major categories of factors that influence our behaviours, which in turn influence our health status. These are predisposing, enabling and reinforcing factors. Predisposing factors are generally knowledge, values and life experience that push you in the direction of your behaviour. Enabling factors are generally external issues that either allow a behaviour or prevent it (such as access to information or facilities -- I can drink cleanish water because I have access to fresh water systems; I can't be Spider-Man because I don't have access to radioactive spiders), however some internal issues such as self-efficacy are also considered enabling factors (I'd probably class these more as reinforcing than enabling, but there is an overlap, so whatever). Reinforcing factors are primarily the attitudes and actions of those around us. If your network encourages and supports a behaviour, they'll also reinforce it; if they discourage a behaviour, they'll reinforce not participating in it.
Taking into account health behaviours (positive and negative -- most behaviours I can think of are one or the other or a combination of the two, rather than neutral) across the six health dimensions as well as things we can't control (eg you don't normally get a say in whether or not you have spina bifida), we can then place ourselves on a continuum ranging from dead or permanent serious infirmity, through to optimal health, with almost all of us being somewhere between those two extremes at any given time. From there, we have the opportunity to improve our health status by modifying our behaviours...if we have the intention and ability to do so.