I’m later mid life and doing 6-10 hours a week on the bike and lifting twice a week. Took awhile to get here but it is possible. I’m doing more aerobic work on the bike, with some intensity. TR plans have a lot of intensity and personally I’d dial back the intensity (way back) when you first start lifting. Like the first 2-3 months. Think of it this way - you are getting intensity in the gym and setting yourself up for long term success.