"The No. 1 rule of investing is to you need to determine your own philosophy and not let the noise distract you," she says.So rather than making an impulse decision to sell stocks after the market has a bad day, you refer back to your action plan and goals. An objective review of your tolerance for loss, personal investment goals and past investment history should guide your decisions. "You don't want to act out of fear," says Bolanis. "You don't want to fall prey to performance envy either." However, Bolanis says not to be too hard on yourself if you do react impulsively and make the wrong choice. "You need to forgive yourself if you make a mistake," she says. "There will always be another opportunity."