I would start programming mobile games, and would hope to make money from them. If I don't succeed, at least I had a hobby, and maybe can use the experience to get a more interesting job later. If I do succeed, then I do not have to solve the problem of boring job anymore.

That would require sufficient freedom to spend those 3 hours not just programming, but also painting pictures, editing 3D models, editing levels, and testing the game on the phone. Okay, hypothetically that is not necessary; there can be some parts that I have to do at home. But it would be much more convenient if I could do whatever is necessary for the game immediately when I need it.

Or, if I wouldn't have a specific plan, I would just learn random stuff from online universities. I enjoy learning, so I wouldn't necessarily care about how useful are those lessons. I would imagine that some part of that would be useful somehow later, if nothing else, then for impressing people.

Someone who is a buddhist could use those three hours to meditate daily, and achieve nirvana in a few years, while keeping a well-paying job. Also, being a buddhist could help with the feelings of boredom from the job. ;)