QUOTE(skylark @ Nov 9 2009, 10:34 AM)

I'm not a natural exerciser, but I've been doing regular walking for the last few weeks, two or three times a week. I do about 1.5 miles each time, sometimes a bit more, and my average time is between 13-17 minutes per mile. Is this enough to get fitter? I'm definitely losing a bit of weight through it. I know what I'm doing isn't a lot by some people's standards, but for me it's a big achievement

Any exercise is better than none. Walking is reckoned to be one of the best. Easy enough for most people to do, intense enough to make you fit, but not likely to lead to injury. 4 miles per hour is brisk for walking, so - unless you are interested in speed-walking, to go any quicker you'd need to start running/jogging. You can probably get all the fitness you need by building up the distances that you cover.
Running is a lot more intense than walking. The benefits come quicker (you become thin very quickly) but against that there is a much bigger risk of injury or permanent damage. When you first start running it is very intense and muscles ache that you never knew you had. To start off with relatively short distances and modest speeds is very sensible - hardly faster than a brisk walk is fine. When you start running faster the stresses on the body increase enormously so it is wisest to build up slowly. If you stick at it you'll soon be amazed at the distances you can cover with ease, and the speed at which you can cover them. But a word from the belatedly wise (and previously rather stupid). Listen to your body!
QUOTE(skylark @ Nov 9 2009, 10:34 AM)

I've discovered that roads which are flat when you drive along them are actually steep hills when you walk them

I've found that it's easier if you lean into the hill but any other tips would be appreciated!
Yes, we all find this when we get out of our artificial environment and into reality. By the laws of physics you have no choice but to lean in to a hill, otherwise you would fall over backwards! As for running up hills, when you investigate you find that the experts on running disagree as much as the experts on piano playing about the right way to do anything. There are (at least) two schools of thought on getting up hills. One school argues for a high, driving knee lift. The other for a relaxed shuffle. The same principles may apply to walking. I do know that when you are out fell walking a stick is a big help. Not a traditional walking stick, the special hi-tec ones that you see serious walkers using.
QUOTE(skylark @ Nov 9 2009, 10:34 AM)

What exercising do other people do?

I used to swim and run competitively so I am used to hard and lengthy training (not that I was ever outstandingly good at anything athletic). As a swimmer I used to cover more than 20,000 metres a week in the pool, and as a runner I trained anything from 25 to 75 miles a week, at speeds varying from short flat-out sprints to many miles of "survival-shuffle" ... depending on what events were coming up. However, I am unable to run much at the moment because of a chronic foot problem.
So at present I swim to stay fit, just three times a week, for up to an hour each time covering about 3000 metres in a session. I also cycle everywhere (this is Holland - everyone does it) including to and from work - a total of at least 60 miles a week. Finally, I do a bit of styretching and a few strengthening exercises on mosts days.
This is quite a lot of exercise by most people's standards (especially those that are over 50), but one of the drawbacks of having been exceptionally fit as a young person is that after a certain age there is no way to go but downhill - however much you might train.
Better than any of this would be to be 20 or 30 years younger!