I have found 1 Thessalonians chapter 5 verse 18 to be a great help with this. It reads,
"Give thanks whatever happens, for this is God's will for you in Christ Jesus."
Some disappointments in life are small - catching a virus, stubbing my toe, but others can be huge. I make a point of thanking God for whatever I am uspet about, including things which I wish he would change. I do it every day! It's an expression of faith. Whether I have brought this thing on through my own folly, or it has come about some other way, God is in charge, and he has chosen not to change it, so thank you God: you know just what you are doing leaving it in place.
To begin with I found this hard to do, but I have persevered, and the reward is considerable. It means I don't have to be uspet about things in my life any more. That frees me up to care for others (Galatians 6 verse 10).
Sometimes I can see that if it had not been for some disappointment in my life, I would not have been in a position to help someone else, so good has come out of it. But for much of the time, I never see any good coming out of things which upset me, so I have to take it on trust that God is working it out for good. See Romans 8 verse 28.
A related issue is that of shame. The view I have arrived at is that it is okay to be ashamed of something I have done, but never to be ashamed of who I am. God did not make a mistake when he created me. See Psalm 139. So I thank God for things I find hard about myself, knobbly knees or whatever!
David Pennant, Woking UK