At what point does being realistic about the limitations of ageing become ageism? The opportunities we have in life change as we grow older, we tend to think more about what opens up to us with age than the things that are lost; for example we think of when we can legally drink, have sex, gamble, vote, or the things that are expected of us with age like taxes. There comes a point in your life when you realise that some dreams can only be achieved by a certain age, and that once you've passed that age, it's unrealistic to ever imagine achieving those things.
Although for many of those dreams they are not strictly impossible when you are older, the odds are just stacked so much against you that the effort required to overcome the disadvantage of age becomes disproportionate and the reward does not compensate you for the investment. In other words your pursuit has to be driven entirely by the desire to achieve it, as the achievement itself doesn't actually benefit you, if anything it will come at a net cost.
