when I was kid I had all sorts of inventions, not many worked (most involved magnets, lol). It wasn't until later in life that I learned the laws of physics and realized why my inventions didn't work.
What do you consider an invention? If you're looking for a patent the idea cannot already exist, or it needs to be a large fundamental improvement over an existing patent.
I worked as a mechanical designer in the automotive field for about a decade, which I could argue involved inventing, since the machines I designed never existed before. We did go for a few patents, and the costs involved were enormous! Many legal and research fees made it pretty much pointless to pursue. The product was for quite a niche market, a rotary actuator that had built in 'cushions' (normally you need external decelerators, and these were not done by springs/shocks but a rather complex CAM profile)