I've found mindfulness really helpful too. I'm no expert, but I'd say the great thing about it is that you don't have to be brilliant at it right from the start. If you notice the moment when you block something, that's a good start. You don't even need to be aware of what you're blocking at first, perhaps just being mindful of the blocked feeling. When first starting, my T taught me a few different techniques. This can include mindfully eating, or doing a chore like washing the dishes, being aware of all of the sensations (the feel of the warm water) and when your mind wanders, bringing it back again.