Need a natural supplement to counter that

I have this issue going for a long time.My main problem is poor concentration and my mind keep wondering in past unreal regrets and remorses. I tried to tackle this problem in variety of ways but could not succeed.Only thing which so far helped me is taking a small dose of benzo which my masks the system for a little while but then it comes back with drowsiness.
Is there any natural supplement whcih can temporarily replace my symtoms and act immediately like within an 1/2 hr without causing any sideeffects.I know I have to find a long terme solution but in between I have to get it done as it is costing me my job performance and getting myself motivated to do anything except thinking these useless unreal thoughts and feeling remorseful,edgy and regrettful all the time.
Please help me ASAP.This has ruined my life from all aspects and I can not take it anymore.