Sometimes, people have life problems that can be entirely solved by doing one thing. (doing X made my life 0.1% better, PERMANENTLY!) These are not things like "This TAP made me exercise more frequently", but rather like "moving my scale into my doorway made me weigh myself more, causing me to exercise more frequently" - a one-shot solution that makes a reasonable amount of progress in solving a problem.
I've found that I've had a couple of life problems that I couldn't solve because I didn't know what the solution was, not because it was hard to solve - once I thought of the solution, implementation was not that difficult. I'm looking to collect various one-shot solutions to problems to expand my solution space, as well as potentially find solutions to problems that I didn't realize I had.
Please only put one problem-solution pair per answer.
I fixed my sleep in a few weeks using the (paid) online service Sleepio, which has been clinically proven (to the extent I think it's available via NHS prescription in the UK):
It took me from getting 1 night's full sleep per year, to sleeping a full night maybe 6 nights a week.
This was after I'd done my own research study for months trying out lots of different standard sleep improvement techniques - none of which made a significant difference.
Sleepio got me to try various things, and hit on one I hadn't considered, which was that I was allowing too much time to sleep in - i.e. setting my alarm clock too late. So I was sleeping too shallowly. It gradually made me compress my sleep into a shorter and shorter time until I was sleeping deeply enough to stay asleep throughout the night. Problem solved!