When you're bored, you push against time. You focus on time not passing, so it doesn't. When you're having fun, you only focus on the fun; however, the emotions override the focus on setting milestones in the fun, so looking back on it, the fun was short lived, when in reality, it far outweighed the blah of the preceeding week --- at the time of experience.
We need to set more funmilestones. Try to remember what always sticks with you when you remember fun, and what makes it seem more. Repeat those sorts of things when having fun so your life seems more rich and more fun-filled in retrospect. Retrospect fun could be seen as more important even than at-the-time fun, since the memory will far outlive the actual event.