If your garage is detached and looks original to the house, check the jamb width against a tape measure before assuming a standard door will fit - homes from the 1943-1959 window often used openings that don't match today's stock sizes.
If your garage is attached, look at the wall or ceiling shared with the house. If you can see exposed framing, unfinished drywall, or a door that isn't rated, that's worth a conversation, since that shared wall is where fire-separation rules apply and a freestanding garage never has to deal with it.
On either type, check the springs and cables for rust or fraying rather than age alone - mild weather here means a spring can look fine and still be near the end of its cycle count. And check the bottom panel of any original wood door for dry rot at the corners; sun and dry air do more damage to old wood doors in this climate than moisture does. If you're not sure which category your garage falls into, that's the first thing to sort out before anything else.