There is no royal road to changing one's mental behaviors and habits. It's a metacognitive skill and can be developed like any other skill but you'll have to put in the work to develop it. Start by developing an exercise routine that you can stick to, preferably cardio. Then make sure your diet is not full of junk calories. If you manage those two then you'll be on your way to developing higher level cognitive skills and might resolve whatever issues you have with your OCD.