In my, admittedly limited, experience of gym equipment it's ever so hard to motivate oneself to put real effort into it. By contrast, if I set off up the hill on my bike on my way to work at the local school, as I did every day last week, there's a real 300-foot rise in front of me with a target I have to reach and as a result I put my back into it properly. My pulse is usually well over 150 at the top - I think I got about 178 or something a few months ago, which isn't too bad for a middle-aged fart. Get out into the fresh air, Bob - you won't regret it!