Professor Meyer’s advice to young students, or older ones, you are never too late to learn. #1
Some time ago I mentioned in a blog the importance of having your bass set up correctly by a good luthier, with a properly rounded fingerboard. It will cost you, but will give you countless advantages over some of the also rans:- here is a good illustration.
Look up Gounod’s opera “Faust”. In the “Kermess” scene there are a few bars introduction before the famous waltz. The only way to even attempt to play this is all in the thumb position, which is easy if you have your bass set up properly. You put your thumb on the D octave and then sail away merrily all in one position whilst your colleagues are slithering up and down the fingerboard with no hope at all of getting all the notes.