You will never find an answer to this because it does not exist. You cannot be confident by staying positive. Confidence is rooted in realism - being positive helps a bit, but is not necessary. Realism involves acknowledging your worries and sometimes being negative as appropriate. If you stop your pursuit of positivity via biblical and non-biblical quotes and turn your attention to your actual situation - think of what to do, what can be improved, which habits to reinforce and which to break away from, it would be far more helpful and effective than what you have been doing. Because what you have been doing has not been effective - otherwise you'd not be asking for help now - so you need a new approach rather than more of the same (ineffective) stuff. You have tried quotes, have given them your best efforts, they have not helped, so stop trying because you have exhausted this approach.