Quality of Life and Euthenasia
Secular Humanists tell us that we get to decide our own 'purpose' in life; Maslow's "Self-Actualisation", where a person fulfills all this final need and thus their potential.
The problem is, what happens when a person becomes unable to to achieve what they view as their 'purpose'? Or when they can no longer do the thing that makes them 'feel' complete? If you are the sort that buys the secular humanist line, life becomes not worth living.
Sooner or later, everyone gets to the point where their independence and physical abilities are seriously degraded. Pity the person who finds their purpose in 'self-actualisation'.