I am not the most coordinated, and I only learned how to ride a bike, period, at 50. I started learning how to mountain bike a year ago, at 51. My progress on the mountain bike appears to be a bit slower than other newbies I know - but they have much more experience in road riding than I do.

It is all good, just focus on having fun! I highly recommend a skills clinic, that will insure you have the right tools with which to build your mtb skills set.