The 69-year-old actress discussed her romance with the 64-year-old actor in an interview for Porter magazine. Hawn and Russell have been together since 1983, following the latter's divorce from wife Season Hubley.
"A lasting relationship isn't about marriage," she told the publication. "It's about compatibility and communication. And you both need to want it to work. If one person does not want it to work, it isn't going to work."
"It's also about not losing yourself in each other," she elaborated. "Being together, two pillars holding up the house and the roof, and being different, not having to agree on everything, learning how to deal with not agreeing. Everything's a choice."
Hawn and Russell first met on the set of The One and Only, Genuine, Original Family Band in 1968, and reconnected while working on Swing Shift. The actress was also previously married, and has two children, Oliver and Kate Hudson, with second husband Bill Hudson.
Hawn last appeared in The Banger Sisters with Susan Sarandon in 2002, while Russell recently portrayed Mr. Nobody in Furious 7. The actor is scheduled for new Quentin Tarantino film The Hateful Eight and BP oil spill drama Deepwater Horizon.