determined
"We don't worry about the weather," she asserts determinedly, "because it's going to be sunny!"
The two leaders presented a determinedly upbeat picture of everyday life in the country.
She stepped back and then turned and walked determinedly away.

SMART Vocabulary: related words and phrases

Strong-willed
adamancy
adamant
adamantine
adamantly
aggressive
gutsily
gutsy
gutty
hard-boiled
hard-headed
pertinaciously
pigheaded
pigheadedly
purposeful
purposefully
ultra-serious
unbending
unbroken
undaunted
unmovable