Regrets seldom achieve anything positive. They only make you feel bad and stupid and thoughtless. And usually the thing you regret is over and done with and you can't rewrite the past.
I don't have any regrets, but there are many things I'd like to have done but didn't, which is rather different. And I don't wish I had done those things, I'm simply aware that I could have done them but for one reason or another I didn't. I don't see those things as a big failure in my life.
I'd like to have lived closer to my mum when she was going downhill mentally and physically. I'd like to have been able to drop in every day or two to see how she was doing. But I was 350 miles away in Belfast so that was impossible.
I'd like to have learnt to play a musical instrument, but I wasn't encouraged to do so and my first attempt at piano lessons went badly; my piano teacher declared me unteachable. But maybe if I'd tried again later in my childhood, it would have worked out.
I'd like to have been a successful novelist, but I simply didn't have the intellect or imagination or self-discipline to complete a novel. I did give it a try but after about 100 pages I hit total writer's block and couldn't get any further.
So I don't regret any of those lapses. I'm very philosophical about them. I could have done all sorts of things but for lack of talent or inclination or because of circumstances they never happened. So be it. Che sera sera.