"Have you noticed that when someone pays you a compliment, you feel good and if somebody criticises you, you feel bad? The suggestions of others definitely affect your mind in some way or the other, big or small. Think about the effect of your own suggestions to your mind; you are suggesting something to it all the time. Will your mind not get affected by your own suggestions or self-talk? The answer is a resounding yes."
"Auto-suggestion or self-affirmation is the process by which an individual trains his subconscious mind to believe something, or systematically deliberates on his own mental associations for a given purpose. It is a conscious endeavour to regulate your mind with thoughts and behaviour in a positive or in a desired manner. Athletes and top professionals reinforce their belief systems and direct their energies based on self-affirmation."
"The dictionary meaning of the word suggestion is 'call to mind by logic or association.' So what you speak to yourself is important, as the mind tends to associate itself with it. The impression of the auto-suggestion self-talk is stored in the subconscious mind, which in turn affects your actions. When you think or say negative things to yourself, negative impressions are stored in the subconscious mind and thus chances of success are reduced. But when you think and suggest yourself positive things, you are making yourself ready for success."
(Apoorve Dubey in 'The Flight of Ambition,' p. 139 Macmillan)