I have been reading my bass clef with increasing speed this week. Sometimes I find myself sight reading (seeing the note and playing it simultaneously) and then I think, "I'm doing it!" Reading notes is not that hard. The secret to gaining most skills is patience and repetition. Take it one measure at a time. Don't worry about speed at first, that will come automatically (and more quickly than you think). Knowledge is not acquired instantly, you accumulate it with experience.
I'm playing my big stand-up bass, and I do get tired standing up too long. So I bought a wooden 29 inch stool from Walmart for only $20. This allows me to play the bass sitting down, sort of. Since the stool is tall, I can still handle the tall bass.
Possibly my biggest musical goal has been to play stand-up bass with a jazz and swing band. However, how do you break in? Where do you start? I could never figure that out. This class, however, appears to be the door.