There's really no substitute for time and miles in the saddle. Just like any physically demanding activity, you're going to have to do it often enough, like every other day, at least, and push yourself to go faster, farther, climb harder, in order to condition yourself for the kind of rides you imagine yourself doing.
The more you do it, the more you will find that your chosen-for-comfort steed is holding you back if you're trying to do more than ride around the neighborhood at 10 mph for an hour a couple times a week.
I rode a lot as a teen, did some other stuff for a couple decades, and made a re-entry into sport about 8 years ago. I put the time into training, adding a second -hand touring "road" bike to my old MTB, then a more modern road bike as I took on longer, more challenging rides.
THe more you ride, and the more kinds of rides you do, the more you learn what your strengths and weakness are as a rider, and you'll be more able to understand what characteristics in a specific bike can make the most of what the rider brings.
Last edited by Ironfish653; 08-11-22 at 10:32 PM.