Is there a word for a person who takes on his own challenge?

I can't think of a word for a person who would specifically choose to face challenges, but there are several names for roles that essentially boil down to that:

• Adventurer


• Daredevil


• Voyager


• Thrill-seeker

Challenger isn't quite wrong too - as one can challenge the inanimate too: a mountain-climber, who challenged the K-2.

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