The Greens have eight MPs, two more than they had in the last Parliament, but although they are stronger than ever before they have again missed out on being part of a government.
"We're not going to sit around licking our wounds," Ms Fitzsimons told NZPA tonight.
"Yesterday afternoon was the few hours that I allowed myself to feel a bit sad about what might have been, now we're totally on the front foot, positive and going for it."
The Greens expect the next three years under a National-led government to be "pretty intense", she said.
"We're the only voice in Parliament now for a lot of the issues around sustainability and we'll probably be the strongest voice for the vulnerable people who even under Labour haven't really been looked after.
"And the big picture, what's happening to the planet, so we have heaps to do. It's good that we've got a bigger voice and we'll be using it."
The two new MPs are veteran environmental activist Catherine Delahunty and Kevin Hague, who resigned as chief executive of the West Coast DHB to stand for Parliament.
"They're pretty pleased to be here and for Catherine it's the third time she's tried," Ms Fitzsimons said.
"Catherine and Kevin are both pretty experienced people, they weren't sitting there with their mouths open."
