Exceeding weekly recommended physical activity levels could offset the harms caused by prolonged sitting.
The World Heath Organisation recommendation, published in the British Journal of Sports Medicine, is part of new global guidelines on physical activity and sedentary behaviour.
In addition, new research, also published in the special issue, suggests increasing physical activity can counter the risk of early death linked to long periods of sedentary time.
"Although the new guidelines reflect the best available science, there are still some gaps in our knowledge," says co-editor Professor Emmanuel Stamatakis of the University of Sydney.
"We are still not clear, for example, where exactly the bar for 'too much sitting' is.
"But this is a fast-paced field of research and we will hopefully have answers in a few years' time."
He added that the guidelines were timely given thecoronavirus pandemic, which has confined people indoors for long periods.
"But people can still protect their health and offset the harmful effects of physical inactivity," Prof Stamatakis said.
"As these guidelines emphasise, all physical activity counts and any amount of it is better than none.
"There are plenty of indoor options that don't need a lot of space or equipment, such as climbing stairs, active play with children or pets, dancing or online yoga or Pilates."
In research involving more than 44,000 people from four countries, scientists have found a high daily tally of sedentary time - 10 or more hours - to be associated with "a significantly heightened risk of death, particularly among people who are physically inactive".
The researchers said 30 to 40 minutes of moderate to vigorous intensity physical activity a day "substantially weakens this risk, bringing it down to levels associated with very low amounts of sedentary time".
The authors also said the findings broadly confirm the recommendations set out in the WHO's global guidelines on physical activity and sedentary behaviour.
But, they added, there is not enough evidence to recommend specific maximum thresholds for sedentary behaviour.
The WHO guidance recommends a weekly tally of 150-300 minutes of moderate intensity or at least 75-100 minutes of vigorous intensity.
But any amount of physical activity is better than none.
Other key recommendations for adults, including those living with long-term conditions or disabilities at any age, also include undertaking muscle-strengthening activity - such as weights, core conditioning - at moderate or greater intensity on two or more days of the week.
The guidance also says adults 65 and over should do physical activity that emphasises functional balance and strength training at moderate or greater intensity on three or more days of the week to enhance functional capacity and prevent falls.
It recommends women do regular activity throughout pregnancy and after birth.
Australian Associated Press