This to-do has two steps:
First, write down all the things that matter to you.  E.g., marriage, business partnerships, parenthood, job , hobbies etc. Compare this to the time when you were young and visualized your future in each of these areas. Is your life today markedly different than what you imagined it to be?Is it for better or worse?
As long as your current life fulfils the things/or atleast some of the things that matter to you in life, you are being authentic. This means you are doing something that makes sense to you, and your current situation , therefore you are being authentic to yourself.
If your current life is totally different from what you wanted it to be even though the same things matter to you even now, it is time to introspect and take corrective action.
As time changes, our beliefs also at times change. Therefore, it is necessary to review from time to time if we are being true to our beliefs.
Second, demonstrate your true self everyday. Be who you are in private in public.