Lots of time.
Sometimes we don't have that much time left on this earth.
My son, who experienced a spinal cord injury - fractured neck
at C-5 (Behind your "Adam's Apple"), 7 months ago-
is now a quadriplegic. (Chris Reeve was a C-2/C-3)
His therapy is designed to help regenerate nerves and re-connect pathways......so he can use his normal skills again. His meds and supplements are to give those nerves an optimum environment.
He's 33 and may live to see stem-cell, nerve implant surgical help.
I'm 63 and doubt I'll live to see him have that, and get restoration of his functions. I also doubt that I have the time for my nerves to re-grow to any significant degree, no matter what my health and regimen may be.