Great advice, unless you’re among the multitudes whose “passion” is not readily apparent. One’s “passion” is not an intrinsic (inborn) characteristic that requires only “letting go.” No. You must actively find and develop it.
How? By searching! Try different things, occasionally invoking the “Risky Business” mantra (“What the F_ck!”). And, don’t give up on something too easily – give it a chance. “Passion” is not a mere interest. It is an interest cultivated through growing knowledge and mastery. (This is the story of most successful careers.)
For example, my father wanted to be a cowboy from a young age. He took this interest and developed it by, e.g., learning how to ride horses, working summers as an actual cowboy driving cattle from Colorado to Texas, obtaining his degree in animal husbandry. This pursuit ultimately culminated in a career as a livestock specialist. (As a boy, he went so far as to sleep with a stick between his knees with his ankles tied together to give himself bowed knees. Not recommended!)
Note: Playing hours of video games does not count as pursuing a passion unless you are a game developer!