How to set up varying thickness of the same line?

[Emin&Trang]

I created a regular curved line and would like to adjust its thickness throughout. It should start as a bit thin, then transition into being twice as think and, towards the end, it needs to get thinner again. Is there an easy way to do this without actually drawing the line on a pressure sensitive tablet? (don't have one).

[Jeff Arola]

You can use Stroke Path with a Brush and under Shape Dynamics have Pen Pressure enabled for Size Jitter.

Then right click on the Path in the Paths panel, click Stroke Path and select Brush and check Simulate Pressure.