Top with the marinade and set the slow cooker - 6 to 8 hours on high or 4 hours on low.
When done, remove the beef from the slow cooker and discard all the rosemary and thyme sprigs.
Shred the beef and add it back to the slow cooker. Tip - If you don't like too much gravy, you can keep the shredded meat separate. Alternatively, you can reduce the gravy in a saute pan over low heat.