Experts said just 25 minutes of brisk walking or slow jogging every day could buy extra years of health - and happiness.
Sanjay Sharma, professor of inherited cardiac diseases in sports cardiology at St George's University Hospitals NHS Foundation Trust in London, said: "When you exercise moderately, you reduce your risk of dying from a heart attack when you're in your 50s and 60s by 50 per cent. That's a really big deal."
Everyone should try to build in such habits to their daily routine, he said.
"Exercise buys you three to seven additional years of life. It is an anti-depressant, it improves cognitive function and there is now evidence that it may retard the onset of dementia," the cardiologist said.
"We may never avoid becoming completely old, but we may delay the time we become old. We may look younger when we're 70 and may live into our 90s."
Cardiologists at the conference said it was never too late to start exercising.
The latest research was carried out by a team at Saarland University in Germany who introduced a group of non-exercising but otherwise healthy and non-smoking people to a staged exercise programme.
It showed that aerobic exercise, high intensity interval training and strength training all have a positive impact on markers of ageing.
The authors noted that endurance exercise and high intensity exercise may be more efficient than just lifting weights, as they further increase telomerase activity, which in turn helps to repair DNA as it gets old.
"The study helps us understand the process of cellular ageing as that's what drives our organ system and body ageing and the effects physical activity can have on the cellular level," said Christi Deaton, professor of clinical nursing research at Cambridge Institute of Public Health, University of Cambridge.
