You are under no obligation to remain the same person you were a year ago, a month ago, or even a day ago. You are here to create yourself, continuously.

Richard Feynman (1918-1988) American physicist

(Spurious)

Not found in his writings, lectures, or speeches. See Who do you think you are kidding, Mr Feynman – Terence Eden’s Blog for more discussion.

It is possibly a misattributed variant of something said by Alan Watts ...

You are under no obligation to be the same person you were five minutes ago.
 

... which may or may not actually be authentic, either.