Not too much information on where to rent or the trails here from my end but I would make some recommendations on other fronts.
First, MTB can be a little rough to start with. I would suggest doing some road work with bikes first. Even if you are a runner you will find that you are using different muscles and it won’t be the same. You are in pretty good shape so doing some basic road work will be easy. I would go climb some hills after warm up to get legs use to the hard push.
In MTB you have those constant little challenges of having to get over this little hill or that stump so you legs have to be ready to do a little peak performance push… Even on the easy trails. If you do a little prep work MTB will be more enjoyable and your first time out won’t be a tiring miserable experience.
If you are one of those guys that do spin classes…
Then you are more than ready to tackle MTB.
Also… Not to offend but the tracks here locally aren’t that tough. They tend to be more XC class than technical so again it won’t be a blood-fest. I rode a lot in AZ where the trails were very technical vs. what they have here.
I also agree with spd about the danger levels. For the most part you make it as dangerous as you want it. That being said even walking down the street isn’t without its risks.
Lastly before you go out on a MTB trail for the first time try out several bike with varying tire sizes first. This is a major choice for today’s MTB’er. A couple of years ago there was only one choice… 26″ wheel. Now there is 29″ and 27.5″ that serves as a compromise for those who don’t like the 29″ wheel. The 29″s feel strange if you are use to a 26″ but roll over everything much easier and since I don’t think you are biased like other having rode the 26″ for years you might prefer it making your first time out a bit more fun.
I think you could start out on some of the intra-canyon space open space trails as a nice first start.
Hope this helps…
BTW… Rode BMX from the ages of 6 to 18… Migrated to MTB during my college years (riding as much as 1500 Miles a month) then doing some road work when I was a consultant…
