First part: Lot of people who workout barely do any cardio, there's even this belief that cardio will make you lose muscle mass, but unless you're an athlete it's completely ridiculous to worry about that. The people that are in the best all around shape are very often not the ones who look the most fit or that are the strongest. We need fat on our body as an energy reserve, just doing cardio doesn't build enough muscle mass to slow down the effects of aging on it, just building muscle mass without doing cardio means your heart might be the weakest link in your body...

Second part: Not sure, I guess they mean that it takes a while to not feel fine from the damage accumulated from not taking care of yourself and by the time you don't feel fine anymore most of the damage is irreversible... I guess it's true for many things... If you damaged your knees from being overweight for a long time, suddenly losing weight won't make the cartilage reappear for example...

I recently had a heart attack at 41.

I'm not obese and look and feel fit and well. I cycle regularly and don't eat a lot of refined foods (particularly carbs). I didn't think I was particularly "fit" but nor did I think I was at risk of heart disease. About 2 months before my heart attack I rode my mountain bike 150km over rough, remote, Australian terrain in 4 days.

Yes I have high cholesterol, have been a smoker in the past, and a family history of type 2 diabetes - I knew these things were problematic in some vague sense but no idea how they relate to cardio problems. Also information is very complex - there's a lot of misinformation about cholesterol for example and as someone who is not a cardiologist it's hard to know what it really means.

Basically, shit builds up in your arteries over time. You feel 100% fine until something clogs up. It's not a progressive deterioration of feeling unwell and not doing anything about it, it's fine > fine > fine > fine > dead. There's no therapy to clean the shit out of your arteries, it doesn't get reduced over time. Once an artery clogs the options are inserting an internal scaffold, or taking an artery from somewhere else to build a by-pass.

I kind of got unlucky but also lucky - unlucky with all of these contributing (mostly hereditory) factors - lucky in that my arteries are generally ok - there was only one bad spot which could be remedied with an internal scaffold. Imagine feeling fine through to your 60s and then finding that your arteries are generally fucked with many trouble spots.

I shouldn't be alarmist in that I don't think this is a problem for people generally, but in terms of things I recently learned that everyone should know - I think cardiovascular health is definitely on that list.

Suffice to say I recently learned that feeling fine does not necessarily mean that you are fine.