Maybe not as intense as some other workouts here, but i typically just walk(fast) either 2 miles or 3.6 miles depending on how energetic i feel nearly every night at like 11pm when its nice and cool and quiet outside...i try to run atleast 1/4th of it or as long as i can before i get winded...i figure it'll get easier as i keep doing it. Just put on a radio podcast or an audio book and 30 mins to an hour later find myself back at home not even really realizing ive been out excersising
Never have been a fan of "working out"...
so, basically your'e doing interval training. Try to have a 1:1 work/rest ratio. Meaning, to start out, run hard for 1 minute, then walk for one minute. As this gets easier, move up to running 2 minutes, walking 2 minutes. Eventually work up to 5 minutes each, and then once you've mastered that, go to a 2:1 work/rest ratio (2 minutes run, 1 minute walk) and you should see big improvements fairly quickly by pretty much doing what you already do, just with a little modification