It can certainly be suggested that as we get older we become surer of who we are, but the potential to grow always remains throughout our life, no matter what. A central notion of the work of Carl Jung was that we should always seek to grow; that, despite never being able to reach an 'ideal' state, we should always be reaching to be the best, and the highest, we can be. The challenge though, comes not in realising this but in putting it into practice on a daily basis. How and what can I do to motivate myself to take action? Here is where the rubber hits the road.
In youth this may have unconsciously took the form of heroes, people whom we looked up to and admired for their qualities. While it may be tempting to think now of this idea as a childish one, especially in adult life, really it can still serve to propel and move us forward through the trying process of growth and change in our own life's.
By looking to other people's achievements we get a glimpse of what is possible inside ourselves, and in our own life, and most importantly that there are other ways of living. We are not stuck permanently as we are, we are allowed to choose another way, if we wish.
If you find your self stuck, lacking inspiration or motivation then find people, or books, or videos which rekindle your inner fire and visit them daily. Keep them, as Marcus Aurelius called it, as your 'dogmata', your place to retreat and return to when needed, to re-motivate and re-align.
For me at the moment this is watching the short film titled 'Portrait of a Dancer: Lauren Cuthbertson', which is where the image above was taken from. Do check it out, I imagine you will enjoy it, and in closing remember that at your hands you have the life's of many others who have already trod the path you wish to walk, use their actions and words to light better the way you wish to go.