Health was commonly known to be: the level of functional and metabolic efficiency of a living organism, as well as being free from disease. Based off of this definition, do you consider yourself healthy?
Striving to become the best version of yourself is not the easiest thing to do, because there are so many facets to work on. Take today to focus on one thing that you want to make better about yourself. Not change, but make better. Do not actively try to think about it, however if you catch yourself slipping back into a negative cycle of the thing that you are working on, take a breath, acknowledge it and try again. Life isn't a "hit or miss". It is about changing; adapting. We are adaptive creatures meant to take on anything.
Now, look at this definition by the WHO (World Health Organization). They define health as "a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity." (1948). Think about this for a minute. Think about how society and those around you think about being healthy. Did your opinion about yourself being healthy change? Did your view of your health change at all?
You are unstoppable. You can better anything that you put your mind to; physically, emotionally or mentally.