Dr Amit Saraf, director of internal medicine at Jupiter Hospital, said all three options of walking for 1 hour, 30 minutes or taking two 15-minute walks can work. "One single 1-hour walk...keeps...heart rate up longer, assisting with continued fat burn. Two 15-minute walks...or one 30-minute walk break up hours of continuous sitting...which can help regulate blood sugar levels," Saraf added.