The best source of internal motivation is from

A. relaxation.

B. positive self-talk.

C. coworkers' approval.

D. a good job.

In my opinion, the best source of internal motivation is: (B) positive self-talk.

In order to increase one's motivation, it is important for a person to be able to talk highly to themselves which increases self-esteem which in turn leads to increased motivation. If for example, a person wants to attempt a daredevil stunt, he/she must be able to talk himself up and convince himself that he can do it.