You know it depends on the amount of loss. If you lose a huge amount, then it’s understandable that you may find it hard forgetting it. But since you are gambling, then whatever loss you had in the past should not be carried away at the present. Do not gamble to chase your losses, nor chasing for luck to make big wins, but just gamble at your own risk.
For me, I’m just an average gambler so my losses are not that significant, I just recover from them easily. And I think that’s the right thing to do, you don’t let your past losses define your future gambling outcomes. Gambling market is unpredictable, and so are the outcomes.