Do what you think you can do. Open your mind to who you can be.

A passage from Johann Wolfgang von Goethe's (German writer and philosopher) play Faust:

Until one is committed, there is hesitancy,
The chance to draw back, always ineffectiveness.
Concerning all acts of initiative (and creation),
There is one elementary truth the ignorance of which kills countless ideas
And splendid plans:
That the moment one definitely commits oneself, then providence moves too.
All sorts of things occur to help one that would never
otherwise have occured.
A whole stream of events issues from the decision,
Raising in one’s favor all manner of unforeseen incidents, meetings and material assistance,
Which no man could have dreamt would come his way.
Whatever you can do or dream you can,
Begin.
Boldness has genius, power and magic in it!
Begin it now.

(W. H. Murray in The Scottish Himalaya Expedition [quoting John Anster who in turn paraphrased Goethe’s Faust in the final two sentences of the preceding quote from Murray]).