Everyone seems to assume the curve starts to shoot up at x=0. I always imagined the steep learning curve's steepness as starting at x>0, thereby creating some stalling or slow growing plateau requiring the bulk of the effort before you reach a certain point where there's a huge, rewarding jump (some "aha" moment) that releases all the build up tension. Compare A (constant, please mentally unjag it) vs B (steep):

    |    A  _.-----
    |     _/ /
    |   _/  /
    | _/   /
    |/    / 
    |----'  B
    +--------------