What's the point of being so precise about measuring your heart rate? As opposed to just exercising? If you're huffying and puffing and sweating I'm thinking that good. And probably the same "target zone" that a heart rate monitor would measure.
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!
At 178 you're getting close to the red zone
I did not know there was any fresh air in London
I'm trying to live my entire life in the red zone, mate!