Am i too old to keep building?

I’ve been using ERG. Tomorrow I have a number of 20 second intervals so I’ll use resistance for a workout for the first time. I’ve got great ventilation.

I understand I don’t get to coast or enjoy the mini respites of slight down gradients.

I don’t suspect that the Kickr power reading is off. I’m just surprised at how much harder it feels on the Kickr and am curious to learn about the experience of others.