Excerpts taken from an article on CNN By Guy Winch:
ON REJECTION:"Rejection is assumed to have developed as an early warning mechanism to alert us when we were in danger of being kicked out of our tribe, which in our caveman past would have been a death sentence. That is also why rejection makes us feel so detached and alone; it destabilizes our need to feel that we belong."
ON BROODING:"Reflecting on how you felt after a painful experience often leads to the kind of understanding and insight that reduces emotional distress and allows you to move on. But when you brood over something, you're simply replaying the same thoughts, memories or worries over and over, gaining no new insights and making yourself more upset and angry.
Ruminating in such ways can be "addictive" in that stewing over such memories or thoughts makes them more distressing, which in turn makes the urge to brood over them even more compelling. These ruminative cycles not only increase your emotional distress in the moment, but over time, the stress hormones that are released into your bloodstream can put you at increased risk for cardiovascular disease."
ON SINCERE APOLOGIES:"When people feel guilty after having apologized for their actions, it's usually because their apology was not strong enough to elicit true forgiveness from the person they harmed. People often leave out the most important ingredient required to make an apology effective: expressing clear empathy for what the other person felt and went through.
Once you convey that you truly "get" how the other person felt and demonstrate a clear understanding of how your actions (or inactions) affected them, they will be much more likely to convey authentic forgiveness, and your guilty feelings should ease soon thereafter."
ON SELF-ESTEEM:"People with low self-esteem should use self-affirmations. Self-affirmations are statements that reinforce those qualities and attributes that you believe you already possess, such as "I would be a loyal, caring and supportive partner" or "I'm responsible and motivated, and I have a great work ethic."
Making a list of your best qualities and writing a brief essay about why a specific quality is important (and how you've expressed it in the past) is a much more effective daily habit for people whose self-esteem is low."
Of course these don't apply to every situation depending on where you are in your journey, but good things to think about, nonetheless.