I am an anxiety prone person, respond badly to stress and I worry about everything. However, I am also rational and, while some forward and contingency planning is a good idea I do realise that worrying doesn't solve or help anything and is often corrosive of one's own life and upsets others. Therefore, I try to take myself in hand and stop the stressing.
If I wake in the night now I say, 'Bad brain chemistry. Things will look better in the morning,' and distract myself with 'fluffy' topics.
I do 'the life audit' which I taught myself to do years ago. Even if bad things have happened or I have lost something I had I do the 'Pollyanna' thing and 'count my blessings'. I ask myself what's good about my life and what I value. I find I can be grateful about many things: living in a free and decent country, free healthcare , education and benefits, a pension coming at 65, a lovely house and garden, beautiful nature, reading, culture and the Arts, lovely children and so on.
Additionally, there is also the comforting idea that failures and disasters can be recovered from and even learnt from. I failed two driving tests but passed the third. I didn't get to do a masters degree but had a great career otherwise. My DD didn't get into Oxford but met the love of her life and (now) fiance at another great university at which she attained a first. My DS nearly had himself thrown out of sixth form but recovered enough to obtain a degree and a great job in a charity. And so on.
A few years back when I was teaching and heading for a breakdown and sometimes wished I could go to sleep and not wake up I forced myself to realise how devastated my family would be if I did anything silly. I said to myself that if I didn't care about my life for my own benefit I could use it for theirs. Incredibly, thinking of them gave me a purpose and cheered me up. Though retiring from teaching was the gift that went on giving!
I think that it is hard for someone like me who is quiet, reserved and had a pretty tough early life to be too optimistic but I find that making myself be positive and thankful gets me on from day to day.
The other day I watched a squirrel scampering around the pear tree and thought I was blessed.