Among my many projects is a long term one: making a mosaic all the way up the staircase. I've just finished the 2nd step, only 11 more to go!
Whenever I find enough money to buy more grout and tiles, I plan the next literal step. The very bottom steps will probably feature shrubs found along the coast and the higher steps change the scene from waves to sky. I keep returning to these steps to clean the tiles or add different-coloured grout to make some elements stand out more. It has taken me about 5 months to complete these steps, in my initial enthusiasm, I thought I could complete one scene per weekend but there are too few free weekends for me to accomplish such a feat. I forget that I also need to work, shop, do chores, excercise, socialise, eat, sleep and wash. Existing takes a lot of time that could otherwise be spent on creativity.