determined

Synonyms: bent bent on buckled down constant decided decisive dogged earnest firm fixed hard-asnails hardboiled intent mean business obstinate on ice pat persevering purposeful resolute resolved serious set set on settled single-minded solid steadfast strong-minded strong-willed stubborn tenacious unfaltering unflinching unhesitating unwavering

Antonyms: flexible hesitating irresolute vacillating wavering weak