Manifesting doesn't work, not in the sense of just wishing for something and it appears. But, there is something to be said for having a positive mindset and believing things will work out.
I am where I wanted to be, but from a combination of factors, hard work, a decent amount of luck and having acceptance that sometimes things go wrong, but that's just life. Negative people get bogged down when something goes wrong, they don't take chances as they're so pessimistic they feel there's no point, or they worry about what might go wrong. They expect only the worst and then that's what they generally get. Partially because they cannot recognise that there might also be some good in the situation. I'm not saying every situation has a "good" side. Obviously things like serious illness, bereavement etc are different. But if say, you don't get a job you wanted, a pessimist will see all the negatives of that, whereas I might be disappointed, but I just accept there's a reason I didn't get it, it obviously wasn't for me, something better will come along etc.
So I guess rather than actively trying to manifest anything, I just trust things will work out in the end. Then I find they usually do.