Uhg its bloody hard.
When I started mtbing I already used to run lots, so I had pretty good fitness, and had ridden loads of bmx before, so that helped loads...
but foraward 20 years, too much work, cars injuries, junk food and general stupidity and putting on an extra 20...25 (ok maybe 30kg) and loosing any fitness i ever had...it is not very very hard.
I am doing some of the longest rides I have ever done...on the road, on a road bike. but even then they are very slow. But my fitness compared to this time last year is MUCH better, been trying very hard, running, riding. Now I just have to get soem strength and skills back and loose some more tonnage and we'll be looking good. Luckily I don't have a job so can do whatever whenever
Biggest issue I have now is that when I try to push hard it just plain destroys me.
2003 Yeti ARC, 2008 GT Zaskar Reissue
, 2012 Cannondale Synapse 3 Carbon (broke), 1996 GT Xizang
2012 Cervelo R3, 2015 Look 675 Light, 2015 Scott Spark 710