There's that saying...whatever doesn't kill us makes us stronger. In the midst of pain, it can be quite a challenge to be patient and tough, much less to look ahead and think it will be useful at some point.
However, in hindsight, I can see the truth of Ovid's statement. One instance of pain from my life has been associated with the death of loved ones, in particular my parents. Experiencing that pain has caused me to learn to grieve, to be independent, to appreciate the loved ones still with me, and to be compassionate toward others who are grieving.
The pain of addiction reached its peak for me in my early thirties. I have been patient and tough enough to hang in there in a 12-Step program for decades, and the pain of addiction gave way to brand new and successful methods for dealing with life other than substance abuse.
Conflict--now there's a fun subject, one most folks would prefer to avoid like a root canal. The pain of conflict teaches us problem-solving, boundary-setting, compromise, and the ability to see something from another's point of view.
Physical pain from an illness, injury or lack of movement, while tough to bear, can be very useful if it leads to changes in behavior that support our well-being. It gives us empathy for others in physical pain.
Finally, I'd have to say that the mental/emotional/spiritual pain I have experienced has probably been the most useful. With decades of patience and toughness expressed in tears and rage, that pain has exposed limiting beliefs and character defects that definitely were not serving me. I've learned to value the unique individual that I am, quirks and all. Feeling comfy in my own skin--priceless!
Still patient and tough,