We humans are not programmed for forgiving, it is one of the hardest things to do. It may be that we need to forgive ourselves first if we are to learn how to forgive others. If we are struggling with ADD or ADHD we likely have a lot we need to forgive ourself for.
1. since I am really no good at forgiving, one of my best strategies is prayer. I find that it works, but often very slowly.
2. lists – I am a big fan of lists. it helps to list all of my grudges and resentments, including those against myself. this seems to somehow weaken their power.
3. can you identify the main critical voice you hear? Maybe it is your somewhat harsh critical father. Maybe you can demote him and put your loving grandmother in charge of the criticism committee. What would she say? (obviously modify this to fit your own situation)
4. Talk about it, to a therapist, a priest rabbi or minister, your significant other(very carefully). Just talking will help, they may offer some valuable insight or even advice. If you are trying to forgive someone else, it may help to talk with them about it, very cautiously and with careful planning and perhaps consultation before hand. sometimes this is best done by letter.
5. do a penance (this may evolve from #4). some appropriate contribution to charity or some other way of helping someone else, and then you can consider the accounts balanced.
6. You may have some other techniques. it is worthwhile to pause and reflect – is there someone (or more often, ones) you need to forgive. and how about yourself?