I guess I'm revealing my age, but you know, there is really no age limit to rock yet. Music, like life, is a journey and a learning experience. You have to do what you love to do, even if it means working a McJob to make ends meet. Eventually your desire will be known to the universe and it will unfold for you. This is my belief.
Many people give up after some difficulty.
Perseverance is key. There are plenty of people out there with no more knowledge and education than me that are happy and successful in what they do. The key is to go from your heart, because if your heart is not in it then you will be miserable, and that's no way to spend your few decades of existence on this earth. At this time I still enjoy folk rock and stuff like the Jayhawks, Steve Earle and that whole Amercana, rebel roots stuff. I have been able to really look around and sample a large variety of artists over the computer- what a great tool.