Quotes and aphorisms about biggest challenges Barack Obama Abdul Aziz Al Ghurair Oleksandr Usyk Neil deGrasse Tyson ,, When we see animals doing remarkable things, how do we know if we're simply seeing tricks or signs ... Diane Garnick Paul Ryan Michael Dell ,, One of the biggest challenges we face today is finding managers who can sense and respond to rapid ... Brian Behlendorf Michael Gerber Vitali Klitschko