I agree, Ian, it's a pretty lame article. I find it hard to believe that grocery shopping burns 155 calories, and then for swimming, it doesn't even give a calorie count. Basically, the article could have just said "do anything but sit or lie down for 30 min."
Off the top of my head, here are my suggestions for burning calories without a gym (most don't require 30 min):
1. Exercise while watching tv (do stretching, leg lifts, etc. on the floor, or walk in place).
2. If your home or building has stairs, make it a goal to climb 500 stairs a day.
3. Don't have weights? Use canned foods, or empty juice or soda bottles filled with water as weights.
4. When you drive somewhere, park a bit away from your destination. You'll get a little extra walking in and maybe provide a random act of kindness along the way (maybe the closer parking place will be claimed by someone who really needs it).
5. You have access to hundreds of personal trainers in your home. Use youtube and other internet sites for workout videos, yoga or dance instruction, interval workouts, etc.
6. Fidget. Fidgeting burns a few calories an it increases your metabolism.
7. Keep cool. In cool weather, don't keep your house too warm. Your body burns calories trying to keep your core warm.
Age 61, Height 5'9"
March 2010 145 lbs, Jan 2013 173 lbs
1st Goal 145 lbs 5/25
New goal 140