But as far as supermodel-turned-supermum Gisele Bundchen is concerned, this one factor can be a make or break: acceptance.
Speaking with MindBodyGreen, the 38-year-old dished the deets on her 11-year-relationship with NRL quarterback Tom Brady, specifically touching on how they keep the love alive.
“We accept each other for who we are,” she told the publication. “We’re not trying to change one another.”
The old ‘opposites attract’ theory also rings true.
“Tom is very grounded. His energy is very cool and collected. He brings that energy of a safe port,” she explained. “I’m more emotional and spontaneous. I bring some of that to his life and he brings some of that grounding to my life – it feels like a really good dance.”
As for practicing what she preaches, Gisele reckons staying in the present moment (with the help of yoga and spirituality) is key.
“To accept each other and fully see each other for who we are, that’s huge,” she said. “When there is acceptance, there is no pain. The only time there is pain is when there is resistance to what is… You cannot change what is. If you resist that, it brings suffering. But when there is an acceptance for what is, there is forgiveness and love.”
Clearly, whatever they're doing is working.