-
Now Playing: FDA approves preventative treatment for migraines
-
Now Playing: Young American smokers get half of their smoke through hookahs: Study
-
Now Playing: Ohio teacher to donate kidney to 10-year-old girl
-
Now Playing: Should we be concerned with second-hand pot smoke, especially around children?
-
Now Playing: Could a PG-15 rating be coming to a theater near you?
-
Now Playing: Guys' guide to getting in shape for a wedding
-
Now Playing: First lady Melania Trump undergoes kidney surgery at Walter Reed
-
Now Playing: What is Ebola?
-
Now Playing: Women may not be getting enough information about heart disease, AHA warns
-
Now Playing: Inside the #GainingWeightIsCool fitness trend
-
Now Playing: Consumer Reports ranks the best sunscreens ahead of summer
-
Now Playing: 29 states now affected by E.coli romaine lettuce outbreak: CDC
-
Now Playing: Weight training can help shape the body and also the mind, studies show
-
Now Playing: New recommendations for prostate cancer screening
-
Now Playing: Try this mother-daughter workout for Mother's Day
-
Now Playing: Firm with ties to Russian oligarch allegedly made payments to Trump's attorney, says adult film star's lawyer
-
Now Playing: Why kids should stay away from sports drinks
-
Now Playing: Mom and 2 daughters lose more than 150 pounds
-
Now Playing: This son saved his mom's life with an organ donation
-
Now Playing: Teen wakes up after being declared brain dead