Depends what you want to say:
Fate: the unchangeable, preordained course of life that will occur because of or in spite of your actions.
Destiny: a series of predetermined events within your life that you can take an active course in shaping.
Of the two, fate is the older philosophical concept and the more pessimistic: According to Greek mythology, the fate of a human being is determined by the three sisters Clotho, Lachesis and Atropos, with Clotho spinning the thread of your life, Lachesis measuring out its length and Atropos cutting it at the point of your death. So, no input from YOU, dearie.
The concept of destiny appears much later and postulates that human actions can influence future and fortune from the outset, a much more upbeat view.
As always, *sigh* context would help.