It depends on the horse, and how 'adult' you are. I mean, some folks thing that starting to ride at 30 is 'old'. Some complain that they'll never get good, since they started at 20 instead of the teeny boppers they ride with.
I started at 41, though I had some distant riding experience from young childhood. I had no choice but to hack out alone. Good thing, becuase at the start I had no idea of what challenges might come my way, so I did not fear them.
But, in any case, there are horses that I've ridden in the last 22 years that I would NOT hack out alone . . ever. Others are a snap. just depends on the horse, and where you will ride.