Hey Duff, and

By attention span I'm assuming you mean within your dream? If so, it shouldn't be too hard to get over that issue. If you can just remember to pick out one thing in your dream (once lucid) - either something in your surroundings or even your own hand - and just sit there and study it, your mind will keep generating interesting visuals for you to look at without distracting you too much to forget you're dreaming.

For instance, you could find a blade of grass so interesting that you might spend the whole dream fascinated by just that. You might start just noticing the color. Then, looking up close you might notice some intricate patterns or something. Even closer, your mind could suddenly put you in "magnify" mode and then you'll be looking at tiny little fibers, and even go down to microscopic levels and see creatures!

Trying to look at too many different things or engage in a variety of actions makes us lose our lucidity sometimes because it distracts us from the thought that we are dreaming. Keeping our attention on something simple makes it easier to keep in mind that you're in a dream.