You are being wise on strenghtening your core. Although my core is somewhat weak considered to others it is considerably stronger than it used to be. I do alot of ab work. My trainer has us work the abs 2-3 times a week, sometimes after our stength training (7-9 minutes) or in between changing sets (50 each time). I have found for me abs on the ball has made my core much stronger. Planks are also very good for core strength. Good luck to you.