I've been (seriously this time) looking into this stuff in practice. I've shifted my state of mind recently for the better. More happiness, less anxiety, more stability and collectedness. I'm pretty sure it's from: 1. doing what I need to do to make myself happy 2. meditating on good feelings. I don't really visualize per say, I'd prefer to call it imagining and I've been slipping into a feel good state more and more often. probably 1-2 times every 1-2 days.
Anyways I bunch of work has showed up for me, easy stuff good paying. Not sure if it's a coincidence or just because it's the start of summer. One thing is for sure, positive imagination does have a good effect on your subconscious... As long as there isn't way too much dissonance between your imagination and reality stimulating negative feelings.