Road riding is easiest for most of us since it is generally right out the door and go. I have a couple of parks and "off-road" connectors from road section to road section near me that I can take my mountain bike on here in St. Petersburg.
One - Weedons Island - has a couple of miles of trails that the director recently CLOSED to bicycles! You go Pinellas County! About as bike friendly as a cactus garden.
Anyway, sometimes you have to make a conscious decision to getting your dirt fix. I really don't like to get less than a 3 hour MTB ride, and if I drive to Santos - 2 hours - I like that to be at least 4 hours ride time.
Boyette and Morris Bridge are about 45/50 minutes from me and both I can spend as much time as I like riding. A complete loop of everything is 25 miles each, and for another loop through some fun sections I can add another 10 or so.
I love riding in the woods way better than riding on the road, but reality is I love biking so road riding gets in the mix. It is tough enough for me to not be able to go MTB because of injury, let alone to not because it's inconvenient to get to.
I know what you're saying as I have found myself in that same position. So I plan my MTB time ahead of time, or go find dirt I can ride in "Bike Friendly As A Cactus Garden" Pinellas County. I don't know where you live, but check some bike shops or Google for some trails nearer to you than 2 hours?