Outside of your family, your mentors are the most influential people in your life.
Unlike your family however, you get to choose your mentors, and with that in mind you should choose your mentors very carefully.
In a career setting your mentor may be your direct manager, but that does not have to be the case. The mentorship relationship can be informal, and is usually an unspoken relationship between a senior and junior person. Whether it is in sport, work, study, art, or any other aspect of life: the first step is identifying a successful person in your field who is accessible to you, and the second step is determining if they are open to you shadowing them in order to learn the ropes.
A good mentor is wise, patient, good at explaining concepts and principles to you, and finally is invested in your success. A mentor must enjoy fulfilling this role, as it cannot be forced.
A bad mentor can lead you badly astray, and must be avoided. I had managers attempt to mentor me in the past who were a fountain of bad advice!
Thankfully I have been blessed with brilliant mentors, I wish the same for you.