KUALA LUMPUR, May 22 — Former Prime Minister Tun Dr Mahathir Mohamad today shared the "secrets” to his nearly-century old existence.

Dr Mahathir is 91-years old, and served as prime minister for 22 years.

Although he retired in 2003, Dr Mahathir has remained active in politics, and is now also the chairman of Parti Pribumi Bersatu Malaysia.

"Many people ask me how is it that I remain healthy.

"1. x smoke, 2. x drink alcohol, 3. stop eating before getting full, 4. always read books," he wrote on Twitter, likely using the cross as a symbol for "don’t”.

According to the Statistics Department in 2015, the average lifespan in Malaysia was 74.8 years.