When people say "Let it go," what they really mean is "Get over it," and that's not a helpful thing to say. It's not a matter of letting go - you would if you could. Instead of "Let it go," we should probably say "Let it be"; this recognizes that the mind won't let go and the problem may not go away, and it allows you to form a healthier relationship with what's bothering you.
Jon Kabat-ZinnMindfulness is about love and loving life. When you cultivate this love, it gives you clarity and compassion for life, and your actions happen in accordance with that.
Jon Kabat-ZinnMindfulness is a way of paying attention, on purpose and non-judgmentally, to what goes on in the present moment in your body, mind and the world around you.
Jon Kabat-Zinn