your comments to close friends definitely have weight, but you can't feel responsible for the healthiness of their egos. In other words, don't beat yourself up if you are unable to cheer up a blue friend with one pep talk. All they ask of you is support and understanding, not the answer to all of their woes. Put yourself in their shoes and you will be able to easily understand that knowing just the right thing to say isn't always required. Your presence, plain and simple, is often enough.