Some background- after some time off I started cycling again last year. Over the winter I was doing a spinning class 2-3 times a week with the occasional ride as daylight and weather permitted. Recently, I have been riding a few days a week and doing around 20 miles on a ride without any problem.

I would like a goal to work towards. I was recently looking at a century ride coming up July 22. At this point, with a little over 6 weeks, I don't think that I can be ready for a full century, but am hoping to do the half century option. I have been doing some reading about training for distance rides. Any suggestions or thoughts on good ways to get ready?

FWIW, the description of the 50 miles is rolling hills with 2 category 5 hills and total elevation gain of 3256 feet. To be honest, that doesn't mean much to me.

If the ride is close to where you live, try to ride the biggest hill at least once in your training. If that climb is easy for you, then the rest of the ride will also be easy. If the climb is really really hard for you, then you need more practice on this or similar hills. For most beginner riders on centuries with thousands of feet of climbing, the hills are way more difficult than the distance. If the climbs are miles long, walking is not an option.

My first 50 miler:
The training:
That summer, I was doing 10-15 mile rides about 5 days a week (on regular undulating terrain - nothing big), with maybe a 20 miler thrown in once every two weeks. I also did a 30 miler early in the summer. All on mild undulating terrain near my home.

The ride:
The 50 was a fun ride, even in the blazing heat that day. I told my wife the route in case I needed to be rescued. I think I ate a PB&J sandwich before leaving. I took a granola bar and two water bottles and drank another bottle full on the way back. This was all in the a.m.

I rode 20 miles, stopped for about 20 minute break (saw a cat I knew and we chatted), rode 20 more miles, stopped for another ~10 minute break, then did the last 10 miles. Felt fine for the rest of the day. Which was funny, because I was spent after a 30 mile ride earlier that year on easier roads.
I was 42 and in average shape. Not a racer or athlete, I just like riding on my own. I don't know how big the hills were, but some required me to look up at them off in the distance. A good 30 miles was all up n down, with the rest undulating terrain.

Sounds like the distance won't be a problem for you, if 20 isn't an issue. Just increyour the length of your rides gradually. 3250 feet of climbing in 50 miles is a decent amount though (not huge, but certainly challenging), so hills are what I'd focus on. Maybe start riding hillier routes and try and increase your climbing speeds and work your way to the smaller cogs. I think if you do that, you'll increase your distance endurance concurrently.

Find your own pace and ride within yourself. Don't succumb to the temptation to start too fast and don't take too many breaks. Assuming you start and finish in the same place, 3256 feet of elevation gain means you'll also have 3256 feet of coasting.

My first 50-miler: I'd been back on a bicycle for essentially the first time in nearly 40 years for maybe 4 months. My bicycle was a comfort hybrid (Radagast in my sig line). I just went out there and rode.

Thanks for the great advice. I have been increasing my mileage and building up to it.

I did the ride yesterday. It was a gorgeous day with beautiful terrain. The ride went well, no problems and I had a good time.