Slightly different perspective from the geezer . . .

44 is still young. When I restarted at 50, I hadn't ridden in 30 years. Sounds like you are riding indoors? If so, what sort of trainer and why do that in southern CA? When I restarted, when it was dry and warm enough, I only rode outdoors, otherwise on my resistance rollers. Back then I just used a HRM watch. These days it makes more sense to use a Garmin. Being cheap, I only buy that stuff on ebay. Since bicycling any distance is going to be outdoors, it made sense to me to ride outdoors as much as possible. So much for the mechanical end of it.

Outdoors, I used miles rather than time, simpler that way. I'd ride somewhere and back. The theory is that one can increase the total weekly distance by 5%-10% per week so to start with, just do what you can. Once a week, I'd ride away from my start until I was tired, then ride back until I was comfortable at 60 miles. I rode mostly on the flat to start with, then very gradually added hills. So this is obviously a way to do that zonal training without getting all formal about it. I think the time for formal training is after one can ride a solo century. Cycling is an endurance sport, so go for the endurance first, then try to get faster.

After I could ride that century, I joined a weekly group ride of folks faster than I was, mostly 60 or so mile rides, 3000' or so. They taught me to ride well. I still ride with what's left of them, 35 years later. Once I'd joined that group ride, I'd do that Sunday ride, then 2-3 20 mile Z2 weekday rides, which was all I needed to be able to ride doubles, events and that sort of thing. On that one Sunday ride, I got my week's dose of the upper zones. I worked up to ~400 hours/year. Beyond that, the curve flattens out.

My wife and I joined our first gym in '79 so we could get strong enough to fish Bristol Bay, which fish fever only lasted 2 years, but we still try to go to the gym twice a week for an hour each time. One day is mostly pulling, the other day pushing. I found that to be very important for endurance. We didn't get big - big is just eating too much. We call it "body remodeling." Weight goes down, muscle percentage goes up. We have one of those electronic scales which measure impedance and translate it into percentages of water, fat, bone, and muscle. Seems to work, helps one's mental state a lot.

We eat a med diet and each consumes 20-30 grams of whey isolate per day, depending on whether we worked out that day or not. For weight loss, besides cutting everywhere, we really try to eat a smaller dinner, seems the easiest meal to short and the most effective.