Hmm, yeah in that case you’re probably best off talking to a fitness or health professional, who can give more personalized guidance. Sorry my unsolicited internet advice wasn’t helpful.

Exercise is great for you, but when you’re first starting out, I’d prioritize consistency and sustainability over intensity.

If you’re just starting to exercise, I’d start by “shopping around” a bit with different activities to find one that you (ideally) enjoy, or at very least feel you can tolerate for the long term. Some forms of exercise might be more “effective” than others, but by far the most effective thing is to find something you can do for 20 years, rather than something you quit after 2 months. Then, once you’ve figured out what works best for you, start easy. You don’t have to be massively sore and exhausted to benefit from exercise. As you become more fit, you’ll be able to tolerate more intense exertion. Most importantly, find a plan and stick to it.

I don’t have a good source for this, but if memory serves I’ve heard 30-60 minutes per week of intense exercise is sufficient for pretty much all of the health benefits.

I think it ultimately depends though. Someone with a more sedentary job might benefit from more exercise than someone who is more active throughout the day (even if they aren’t ‘exercising’, strictly speaking).

Ironically, I think this is partly true. Someone feel free to correct me if I’m wrong, but I believe the human heart generally has a roughly constant number of beats between people of a variety of levels of fitness. One difference is that people with higher cardiovascular fitness tend to have lower pulse rates when they’re not exercising (which is most of the time), so it works out that it takes longer to reach the average number of total heartbeats than for someone who doesn’t exercise.

My advice: Don’t. Instead, push yourself to walk 30 minutes 3 days a week. Then 5 minutes of running, 25 minutes of walking, then 10 minutes, etc, etc.

There’s absolutely nothing wrong with starting slow. In fact, I’d argue it’s by far the best way to start. When you’re first starting something, it’s almost never necessary or desirable to push yourself to the point of failure, or even significant discomfort.

When I started lifting weights, I estimated what I could actually lift for reps, and started out doing half of that much. When I recently re-started running after several years off, I knew I could do 3 miles at 8:00/mi. I started by doing 1 mile at 12:00/mi. I recently ran my first half-marathon. Slow and steady wins the race, because slow and steady actually makes it to the end.