Yes and no
In our careers and lives, it's okay--encouraged even--to say 'no' to a few things.
The person we're not right for, the job that isn't a good fit, the opportunity that doesn't align with our values.
Saying 'no' is a signal that lets us (and other people) know who we are and what we're about. It clarifies the unknowns, and makes us all the better for it.
On the other hand, saying 'no' to everyone or everything is a surefire way to avoid progress.
Because you have to say 'yes' to some things, especially when our options are imperfect, uncertain, or few and far between.