I suppose "bettering" could be interchanged with being more entuned and/or balanced? Yet being such is beneficial and thus "bettering" in that regard?
Th purpose of practice is to develop will power and choice, via the practice needed to reach the goal of perfection. Perfect will take practice.
For example, say you were of average physical ability and wanted to learn how to do a gymnastic tumbling run, composed of several front and side flips and twists, with a stick landing. Under your own original inertia, on your first trial, you will crash and burn, since your innate nature is not equipped to do this; your physical and emotional determinism is set. On the first try you can grind your teeth and will and choose all your want, but crash and burn will happen by deterministic default; pre-defined result.
As you overcome the disappointment and pain, continue to practice and start to pick up the various skills as you condition your body to take the pain of falls, one day you do a reasonable tumbling run, that you could not do when you started. You have demonstrated your will and choice to continue practice against the pain, with this will and chose, over time, able to reprogram your default deterministic origin.
Often in discussions of will and choice versus, determinism, people compare in terms of immediate results. Will and choice appears to fall short of determinism; choose to stop drinking, which works for a few day and then back to determinism. But with practice, we can start with our original determinism; default ability, but with will and choice and repetition to practice, we slowly starts to reprogram the brain and body, until will power appears, to have an edge over the original determinism.
Things like character are not something one is born with. Determinism or default is more connected to seek pleasure and avoid pain. Character takes will and choice to practice good choices to learn over a lifetime, against the inertia of your original innate and the pitfalls of collective determinism. Will is needed for practice, even if the result is initially deterministic crash and burn. But, overtime, practice can reprogram the brain and body of its original determinism; lifetime of practice until character and wisdom appear. One is not born this way, but through choices we make; put into practice, over time, we change the original determinism into choice.
People go to self help groups and lectures to alter their determinism so they can have more choices.