Last night I had a LD where I needed some kind of a boost because I wanted to fly in space… Few times in this dream I had a blackout and I shouted lucidity 100%, and everything came back more vivid and more realistic but still I needed some extra boost.
Then I remembered of Peter Pan and how he used happy thoughts to fly, so I used my happy thought too [and the most funny thing about it is that the happy thought was actually the thought that I became lucid 
] and I was able to fly higher with much less effort then usually.
Eventually I made it, I was above Earth and it was awesome, starting from the ground, passing trough clouds and eventually I could see stars, after that I saw 2 planets and they were to me like ball, I grab the first one, I suppose with my hands and I play with them but after some time I loose the power and I felt on the Earth again, then I tried again but I wasn’t lucky enough this time…
Also in this LD for the first time I realized how important is to have a goal when you became lucid. One of my theories why I had those blackouts is because I didn’t have a goal maybe in another words I wasn’t prepared on being lucid and maybe that cause blackouts because so many things crossed my mind and I just didn’t know what to do…
So my story is that the happy thoughts helped me in gaining more power or “juice” in lucid dream, so if you thing that can help you try it out!
Peace!
!