The third mission Repossession takes you to Simeon. After talking with Simeon, take any car and travel to Vespucci Beach with Lamar.
Once you reach the check point, jump over the fence, and at the end of the street search the last garages on your right for the bike. Local gang members will approach and Lamar will shoot one of them. Pick up a weapon from the ground, and kill all gang members (some of them are on the balcony). Ignite the gas trail to destroy a car. Once your health goes below 50% it will regenerate back to 50% if you remain undamaged for a short while.
At the end of the street jump over fence, take a bike and drive to the car wash.