Some good answers from Nohelp there. just to add, i find listening to gentle soft music very helpful, and meditating too helps you to relax and calm the mind. Best time of day is probably the morning before you start your day if you can.
Plus breathing exercises can help too.
I understand what you mean, and your probably feeling overwhelmed. have you not tried to look into why you feel like you do? what the problem maybe, what it is that's stressing you out. You need to work on that and try your best to sort that out,then you can begin to feel less stressed and feeling like bad things are going to happen to you.
i also understand what you mean by medication to, i dont like it either and always tried to go the natural way. you could also try a Bach Flower Remedy called 'Rescue Remedy' that is used to calm people down, it is mainly for shock but it can help.