merlinextraligh

I don't think it's your age. I think it's the amount of base you have.

40 is not that old. At an extreme example Jens Voigt is 42, and puts in 21 hard days with only 2 off every July.

Personally, I was a Cat 5 at age 47 (admittedly the second time around) and am a Cat 3 at age 55.
I'll do multiple hard days together, and 4-5 hard days some weeks.

I have a teammate who upgraded from Cat 1 to Cat 2 at age 52.

And there are a number of older guys who post in this forum who are Cat 1's and past 50.

So age is not your limiter. It's about what you're trained for. My bet is at this point you may just need to put in a lot more miles. If you got a big base from the winter, it's easier to sustain a higher trianing load when the intensity starts in the spring. And if you have a base of many years of riding, it's easier to sustain a high training load.

It may be that given your current fitness, your training stress to recovery is right for what you can hadnle now. But if you want to reach your potential its going to take more than 2 days a week at some point.

I agree with Valygrl that following an actual training plan will help a lot. If you can afford it, and are inclined to put in the effort, buying a power meter and training with power would be helpful ( buy the book training and racing with power first). That will allow you to measure your training stress and cummulative trianing load, and figure out more precisely how much training load you can handle.