Here are some of my ideas and things I have found have helped.
Firstly take some quiet time for you and let non urgent things wait as they will still be there another time for you to sort with a pen and paper and a cup of tea and shut the door and sit down and make yourself comfy and have a think about what is it exactly that upsets you and why and write anything down no matter how small as things that upset one person don't upset another.
One example is writing down about sibling favouritism which has come up on my list that is a major thing that has brought up anger and resentment in me with things like them getting bought a house when none of us others did, getting into the local grammar school by appeal and I didn't and my brother passed his exam on his own merits which I wasn't cross about, them getting taken to parties and I wasn't and made my own way there and when you look at what's going on its not the surface things in themselves that upset me no what has done is the unfairness of it all which I feel is at the root of the anger and resentment.
Talking through anger and resentment with trusted friends is of help when they reassure you no those feelings aren't irrational and how you only wanted the same things and how I wasn't doing it deliberately to be malicious and that I don't go round planning to have ill will towards anyone on purpose and how things like that can hurt.
Exercise is good as well as it helps to calm you down and anything will do if you enjoy it as it takes you away from what's been eating at you.
Currently I am sorting through anger and resentment issues and have found that its what's behind those things I mentioned above is what has upset me more than the things in themselves and its the unfairness I feel that rankles.
I will work through the anger and resentment in time but it helps to have an idea what it is and why.
Hope this helps.
@Catgirl