You can hem your own pants (yoga or otherwise) in just a few easy steps, even if you don't own a sewing machine. If your yoga pants are fairly close to the right length, this method, based on instructions by blogger Dacia Ray, is fast and easy.
Instructions
Leave the original hems alone for now, and decide how much shorter you want the pants to be. Take that number (in inches or centimeters) and divide it in half. Example: If you want to take off 2 inches, use 1 inch as your measurement.
Fold the pants up so they are cuffed with the insides facing out. (Do not turn your pants inside out.) Measuring 1 inch, or whatever length you've chosen, from the original hem down to the folded edge, pin all the way around the leg. Be sure to keep measuring all the way around for an even hem, and don't include the original edge of the jeans in your measurements.
Once you've entirely pinned both hem, it's time to sew them up. To imitate a sturdy machine-sewn hem, use a backstitch all the way around, sewing alongside and above the original hem. Use the original hem as a guide to create a nice even stitch.
When you're done sewing, trim the excess material leaving 1/2 inch to prevent fraying, and press it down with an iron.
Turn the leg right side out again, and you'll see the pants' original hem. Press the leg flat with an iron, and you're done.
Related Articles

How to Make a Flared Pair of Pants ...

How to Make Knickerbocker Pants

How to Narrow Wide Pants
How to Alter Pajama Bottoms

How to Add Elastic to the Ends of Pants ...

How to Lengthen a Suit Jacket

How to Make Basic Drawstring Pants or ...

How to Hem a Cardigan Sweater

How to Keep a Cuff in Jeans

How to Hem a Formal Dress

How to Alter Pants to Make Them Smaller ...

How to Sew a Dart Into Jeans
How to Keep the Elastic in a Waistband ...

How to Lengthen Dress Pants

How to Make Tear Away Pants

How to Measure Board Shorts

How to Remove a Double Crease

How to Repair Frayed Pants Cuffs

How to Get Pants Like Denim Stiff

How to Alter a Boxy Jacket
Writer Bio
Laura Roberts is the editor-in-chief of Black Heart Magazine and author of the weekly sex column, "V for Vixen," at Hour.ca. She is currently working on her first book, a guide to the sexy side of Montreal.