Ignoring our negative thoughts is tough and can be very difficult to do. Using a metaphor can help. Why not see if this one helps?
Do you ever feel you are being carried away by a swirling river, struggling to stay afloat among mud and debris? The stuff in the river is our thoughts, sensations, events and feelings. The river is our distress as we drift helplessly downstream. But that's not the only option. We can get out of the river and stand on the bank, watching as those thoughts, experiences and feelings go by, disappearing into the distance. It might be helpful to note individual items as they pass - a log representing some thoughts, a rubbish bag of bad experiences which you can throw away.