Affirmations are statements used to overwrite negative thought patterns and bring about positive changes in one's charachter. Our minds spew forth a litany of negative programing. Whether those be from outside influences, or from within, they enable us to become blocked and stagnant. No longer able to move forward we wallow in a mire of self deprecation.
There are a few ways to do affirmations. My personal favorite is verbal. While looking in the mirror, say out loud a positive statement about an area of you charachter you wish to improve. For example, if you have trouble keeping calm in tense situations, you would say "I am able to keep a level head in stressful situations". Repeat this daily, morning, noon and at night before bed.
Writing your affirmations down is another way. Before bed completely fill a page with your positive statement. Continue to write the same thing every night until the desired thought pattern is achieved. If your curious to see how long this takes, keep track by dating each one.
Audio playback is helpful as well. Simply make a recording of yourself saying your positive messages, then listen to them frequently thoughout the day. The idea here is repetition. If you do something enough it becomes ingrained in your mind.