Two thirds of people spend 20 hours a day either lying down or seated, a poll suggests.
Of 1,000 UK adults questioned, 67% said they spend 20 hours or more off their feet.
But the poll, conducted by Weight Watchers UK, found that 54% of people believe that they lead busy and active lives.
Zoe Hellman, head of public health at the dieting and weight loss organisation, said: "The rise in modern technology means we're constantly 'switched on' - from texting and emailing to browsing online, it's mentally exhausting.
"In our heads we feel like we've rushed around all day, but in reality we've hardly moved - 21st century living where everything is accessible to us 24/7 has engineered movement out of our daily routine."