So here's a few tips.
1. Don't live in the past. Don't allow yourself to become captive to past feelings and circumstances. Learn from, but don't dwell on those feelings or circumstances.
2. Refuse to indulge in self-pity. No-one gets through life without some pain. 10% of what happens happens, but 90% is how we deal with it.
3. Don't hold onto suspicion and resentment. Let go. Forgive, focus and move on.
4. Cultivate old-fashioned values - love, humour, compassion - in others words love, laugh and care.
5. Find something bigger than yourself to believe in.
Self-centred people are always unhappy.
Peace is a "heart" condition.