Specifically, if your work is a typical job, it makes your meaning dependent on a business relationship where one side has a lot more power than the other side. Example: an employer may end or modify the relationship for factors that are unrelated to your goals at any time.
In general, depending on work for one's ultimate meaning is dumb because whether or not you worked "hard enough" is judged by other people, not the entity responsible for putting humans (and therefore you) on the planet in the first place--you're already here so you obviously are supposed to be here, otherwise you wouldn't be. Good work makes you deserve to be among others but it can't make you deserve to exist on the planet.