One of life's great lessons is knowing when to refuse. Not only you should know when to refuse others but most importantly you must refuse yourself. There are many trivial things that will seek your attention, sucking away your time from the real important things, refuse them. Keep away from meddling into the affairs of others and keep away others from meddling with yours.
Refuse your friendship to those who you are suspicious of. Refuse the salesman who approaches you in your office. Refuse the desire for immediate gratification.
To refuse one activity frees up time for another. Always give your time to things the matters most to you and always have time for yourself.