Lovely post, but one aspect that I would wish to touch upon ( that you briefly covered) is strength training.
Strength training comes under "Anaerobic exercise".
Basically there are two ways your body burns energy to fuel movement.
Aerobic - with oxygen. This basically is a slow burn, your body draws on the energy stores from your blood (oxygen and glucose both can be used) as fuel.
This is sustainable activity, a lot of what OP described comes under Aerobic activity (except HIIT)
ANAEROBIC - Without oxygen. Here the activity is so intense that your body runs out of oxygen generated fuel and now has to 100% rely on the glucose in your muscles. This cannot be sustained for more than 2-3 min Bursts of explosive activity. Your body produces lactic acid far more intensely than during aerobic and the causes tiredness. That's why your muscles gets sore when you get occasionally lift that heavy suitcase or randomly do 5 push ups.
The body needs both to be fit. In some areas Anaerobic is very vital,
1) it helps reduce muscle loss - a huge issue as we get into the 40's as muscle degeneration accelerates at this age and gets progressively worse as we get older.
Muscle atrophy is also caused by our sedentary lifestyles. Weight lifting (an anaerobic exercise) helps improve muscle mass till the 40's and then helps reduce the pace of muscle atrophy.
What does this mean in simple English? If you lift weights consistently, when you are in your 50's and 60's, you will be a lot more fitter and stronger.
Builds lean muscle and burns fat - Anaerobic exercise is like a chest code in that you keep burning fat long after your work out is done. And the more you do this, the greater your fat burn in future work outs.
Improves bone strength and density - self explanatory. Again, like muscle atrophy, your bones become weaker with age. Boje density is the amount of bone material in your bones and again age + lifestyle + lack of calcium in diets leads to less dense bones.
Again, in simple English, it means you are more prone to fractures and women osteoporosis.
Helps mitigate or reduce chances of serious lifestyle diseases like Heart ailments, back pain, arthritis she diabetes.
This is not a bullet cure for these but someone who lifts and does aerobic exercise is likely to have a lower probability of catching these diseases or delay onset at least.
The best aspect though is the high. Similar to a runners high, pumping iron alleviates depression, and burns stress. And oh, you look sculpted (forget the really built guys here, that takes years of focussed work and in some cases steroids), clothes fit better and relative to people you age group you simply look better.
Include lifting in your exercise plan.
Some common myths / questions,
1) you will get buff like those body builders in the gym - no, just like how driving an hour daily won't make you a Schumacher, lifting 30 mins - 1 hr daily won't make you a Schwarzenegger that comes with years of hard work
2) I went for a day but I had severe, near debilitating pain in my muscles for a week after-
Welcome to DOMS. Delayed Onset Muscle Soreness. Remember that bit about lactic acid and fatigue from lifting that heavy suitcase from the loft? Well the first time you lift weights, you are both using muscles that have atrophied from lack of use and age. Your body is breaking down glucose at an exponential rate, leading to a lot of lactic acid production leading to DOMS.
It is severe soreness. In many cases you might not even be able to walk easily or lift your hands above your shoulders (depending on the muscle group worked), but again as I clarified, the more you lift, the more your body regulates itself (glucose burning + lactic acid production) and the better you get at this and the Soreness disappears.
So when I started 2 years ago, 5 pull ups or bench pressing 10 kg would put me out of sorts for 3-4 days easy. But with time I worked up to a bench personal record of 80 kg (1 Rep maximum) or 60 kgs for 3 sets of 10 reps each and my body would not have any soreness. But then 6 months of inactivity during the lockdown and now I get DOMS for even 30 kg reps.
Depending though on your tastes, many lifters actually love DOMS. I for one missed it and am happy it is back. Nothing like doing a heavy leg day and the next day walking down stairs like you are Shankar Dayal Sharma.
3) I need a PT and they are expensive - PT's in a good gym are very useful but no, you don't need a PT. You have easy work out combos online and this is very very very important, the first few times you do a new exercise, always ask a trainer in the gym for a form check and correction.
3a) what's a form check? Lifting is very precision driven. By changing the angle of your elbow by a few degrees you can work out either the chest or use a lot more stabilizer muscles and dissipating the impact substantially. So the form check where someone experienced checks if you are doing a work out the way you should, is vital. Some work outs can even harm you badly if you use poor form (like squats for instance) but any trainer or even gym regulars will be glad to help you with a form check
Finally
4) every year I pay up on Jan 1st and go for 3 days, never to go again-
Yes this is a big issue, gyms infact count on this. They do what airlines call, "overbooking". Regulars usually stay clear the first week of Jan or change timings as usually traffic can even double but the majority,. 80% drop out after this and never go again.
https://www.independent.co.uk/life-s...-a6797716.html
Only 18% of gym members ever go to a gym regularly which is 4-5 times a week. Another 50% hit it 2 times a week, the rest never show up.
How to get out of this trap? Simple. Show up.
I too have joined at last count 6 different gyms (Talwakars, Planet Fitness, Golds, Fitness One + 2 local gyms) over 10 years and totally must have gone 20 days.
Two years ago though was my own wake up call, after much forcing I did a master check up and the numbers were horrible. While I have never been fat (72 kg has been my max at 5'6), and thus never thought I was unhealthy but, my blood sugar was all over the place, good and bad cholesterol horrible, vitamins and minerals all severely deficient. I could not climb 3 flights of stairs without needing a 10 min break.
After joining, I showed up. That's it. My only goal in the first month was, show up 6 days a week.
Many a time I used to just sit at the gym do one work out and then spend time on my phone. But habits form and now, lockdown aside I have missed more than 5 days in a gym only when I was myself hit by Covid. The key thing I check now when my travel desk makes bookings during my travel, gym pictures and reviews of hotel gyms on TripAdvisor. It's so much of a habit that even if I am travelling to the US or Australia where timezones are a challenge, the first thing I do when i reach the hotel is shower and then hit the gym.
It's just that rewarding.
Do a mixture of aerobic and anaerobic on a weekly basis. Ideally use cardio to warm up (45 mins) followed by lifting. The rewards will be very visible.