Imagine an airplane that flies 100mph. You want to fly north, but you have a 90pmh crosswind from the east. You have to point almost directly into the wind just to keep from getting blown off course. You can turn a little to the north, and you'll go very slowly. If you instead have the wind come from the east, you still have the same problem.

Maybe easier analogy: to get directly across a river, would you rather swim across one going fast or slow?