Where the Founders of Young Startups Find Inspiration From Quirky's Ben Kaufman to Aaron Levie of Box, here's what inspires some of the hottest startups around.

Inspiration can come from anywhere. We asked the founders of high-profile young startups to let us in on what keeps them going when things get tough. From inspiring books and buildings to a kind word from a good friend, here's what inspires them -- and could do the same for you.

Aaron Levie, Co-Founder and CEO of Box

"The amazing thing about the technology industry is it faces constant change. No leadership position lasts too long, any underdog can topple a giant, any problem can ultimately be solved, and everyday a new one appears. The ability to build new and elegant solutions to extremely difficult problems, or even problems people didn't know they had, is what motivates me and everyone at Box."

Related: Six Mistakes Entrepreneurs Make When Seeking Venture Capital

David Gilboa, Co-Founder Warby Parker

"[I'm inspired by my] late friend Mike Morse and the poem 'I'd Pick More Daisies,' which Mike kept on his refrigerator and lived every day. The poem makes me think of him and reminds me to live each day to the fullest."

An excerpt from the poem "I'd Pick More Daisies:"

If I had my life to live over,
I'd try to make more mistakes next time.
I would relax. I would limber up.
I would be sillier than I have on this trip.
I would be crazier. I would be less hygienic.
I would take more chances, I would take more trips.

Neil Blumenthal, Co-Founder Warby Parker

"Jack Kerouac's 1958 novel Dharma Bums is a perennial source of inspiration. As a writer and thinker, Kerouac was spirited and improvisatory but also disciplined in his craft. Of Kerouac's work, Dharma Bums is the most episodic and the most humorous -- it always struck me as the ultimate ode to adventure. There's a lot in his approach for all of us to learn from. The name of our company actually comes from one of Kerouac's early journals -- each new employee gets a copy of the book on his or her first day."

Related: Warby Parker and Inspired Vision

Ben Kaufman, Founder of Quirky

"[I'm] inspired by the Empire State Building. Probably not many people know that it was built in one year and 45 days. It's taken 11 years and we still don't have a Freedom Tower. We have shifted into this world focused on making apps and servers, etc. and forgotten about the things that actually touch all of us as human beings: Real things that you could build or even something that you could just hold in your hand."

Related: Quirky: The Solution to the Innovator's Dilemma

Jeremy Heimans, Founder of Purpose.com

"I'm inspired by people realizing their own power. I see this when someone takes their very first social or political action via one of the movements Purpose has created. They might be 8 or 80. An 8-year old girl recently used our Pressure Cooker tool to save her school in Rio de Janeiro from demolition to make way for an Olympic change room -- when her campaign inspired thousands and pushed the mayor of Rio to create a participatory process to determine the future of the school. That inspired me. That little girl got a sense of her own power."

Related: Purpose and Its Vision for Powering Social Movements

Ben Goldhirsh, Founder of GOOD

I'm most inspired by problems -- problems our business faces and problems our society faces. What I'm most inspired by is how well problems tend to work together, and how that can inspire the solutions we conceive. In society, problems are interconnected -- education problems lead to job problems, which lead to tax problems which work well with infrastructure problems. At GOOD we're working to build a platform that better orchestrates how solutions work together too -- connecting like-minded people working towards the same goal of individual and collective progress across a range of issues.

Related: GOOD on Its New Vision for the Future