All sounds have a beginning, a middle, and an end. Good musicians control these variables. It's called articulation.
    Listen to a great player like Nathan East and notice the length of his notes. The length is controlled for the desired effect. On the electric bass in particular it is easy to just let everything R I N G. Listen for the short and long notes.
    Practice playing a simple phrase with a different articulation each time through. Example: One octave scale with all shorts notes. The same scale with all long notes. The same scale but now with alternating long-short. Then short-long.
    Become aware of the length of notes and your playing will sound more mature and more musical.