Step 1: Cast on a scarf
Step 2: Knit valiantly until the project sucks your soul away
Step 3: Abandon the scarf for 3 years
Step 4: Find project while rummaging through stash
Step 5: Decide to finish the scarf
Step 6: Decide you are too lazy to actually finish knitting a whole scarf (besides, you never liked that yarn anyway)
Step 7: Decide to make a cowl instead of a scarf
Step 8: Pretend you meant to make a cowl all along
Step 9: Hide the evidence Give away excess yarn
Step 10: Marvel at your ingenuity while enjoying your new cowl (or, you know, giving it away for Christmas)

*Steps 3-5 optional