Meditation requires a balance of effort and relaxation. Too much effort makes meditation tiring and unsustainable, while too little effort causes you to lose your grip on your attention. The classical analogy for this balance is having just the right tension on the strings of a sitar. If the strings are too tight, they break easily, but if they are too loose, they cannot produce beautiful notes. So the strings need to be in the "Goldilocks zone" of being not too tight and not too loose.
A very common question among people learning meditation is how to find and maintain this balance. I suggest one fun way of doing it is to play it like a video game. When playing a game on the XBox, it is most fun when the difficulty setting makes the game just difficult enough to be challenging, but not so difficult that you'll lose every time. So I like to start a game at a "beginners" setting and increase the difficulty as I get better at it. We can play the same way in meditation, especially since we get to control the difficulty setting. Initially, we can make the game easy. For example, we can tell ourselves, "If I can sit for just five minutes, and I can maintain a solid attention on my breath for ten continuous breaths anytime during these five minutes, I win!" If you can beat the game at this difficulty setting say ninety percent of the time, you can increase the difficulty setting for more fun. Once again, the key is to create just enough difficulty to be challenging, but not enough to discourage you.
One funny thing I discovered about playing this game is after I became quite good at it, the lowest difficulty setting became really fun. That setting for me is, "Just rest my mind for 10 minutes, in an alert sort of way". That is it, just rest. I like it so much I still play at this setting a lot in between days where I play the more challenging games. It is a game where the easiest setting never gets boring.