No one can construct for you the bridge upon which precisely you must cross the stream of life, no one but you yourself alone.

This quote means that in life, you have to make your own decisions. No one else can decide for you what paths to take and when to take them. You are the only one who can create a plan and make choices that will help you move forward to achieve your goals. You must take responsibility for your own life and be in charge of creating your own path.