What does it take to become a very successful engineer?

Hard work, sacrifice, persistence, hours of research from multiple sources, constant learning to remain current.

influential contacts
find a rich influential uncle to help you get the best jobs
Knowing a sitting US Senator will be an asset

Engineering is a life style. To be a good engineer, you need to have natural curiosity and a mind that can take in information and produce desired output. Any good engineer that I have been around puts in way more than 40  hours per week. Some of that time is spent on learning and projects outside of work.

I've found that contacts with other people are very important. I wouldn't be in the position I'm in without contacts.

I 2nd, 3rd, and 4th oldschool's answer.  Your success or lack thereof lies in your hands alone.