Don’t take it personally when someone turns you down. Assume they are like you: busy, occupied, distracted. Try again later. It’s amazing how often a second try works.
Life is too short to wake up with regrets. So love the people who treat you right, forget about the ones who don’t, and believe that everything happens for a reason. If you get a chance, take it. If it changes your life, let it. Nobody said life would be easy, they just promised it would be worth it.