The three dimensions of space allow us to see three-dimensional shapes, like cubes and spheres. If we lived in a world of two-dimensional space, we would instead see squares and circles with zero thickness. Stephen Hawking has said that such a two-dimensional space could not support life, as a 2D being could not both eat and defecate. A shape with two openings could not hold itself together, and would fall apart or bleed to death (try to draw it and you’ll get the point).
Decade 2: Go to school
Decade 3: More school and then work
Decade 4: Make babies and watch them grow
Decade 5: Work a lot so that you do not need to work forever
Decade 6: Empty the nest and maybe retire
Decades 7 and beyond: the rest