The recommendations for healthy adults to maintain health and reduce risk for chronic disease are as follow:
At least 30 min/day of moderate-intensity aerobic activity at least 5 days/week for a total of 150 minutes
At least 25 min/day of vigorous aerobic activity at least 3 days per week for a total of 75 minutes
A combination of the two + 8-10 strength-training exercises with 8-12 repetitions of each exercise twice/week
References: The U.S. Department of Health and Human Services (USDHHS), American College of Sports Medicine (ACSM) and American Heart Association (AHA)
Choose activities that you enjoy and can do regularly. You just need to keep it interesting by trying something different on alternate days.
Every bit counts, and doing something is better than doing nothing!