If you regret smoking when you could've done something else that you'd enjoy more, it sounds like you aren't smoking at the "right" times. The best way to enjoy a recreational substance is to do it when it will enhance your experience of a certain time period. If it takes away from something you'd rather be doing at the time, then it obviously isn't a good choice to do it... but if you have nothing important to do, or at an event/party, or it helps you in a certain situation (work/school) without detracting from your ability to perform, then those are a few examples of good times to smoke.