The book Flow by Mihaly.

There are three conditions needed to enter flow. First, attention and motivation must be directed at completing a task or achieving a goal. Second, there must be a reasonable level of challenge attributed to the task/goal in order for flow to happen. If it is too easy you will get bored and if it is too difficult you will give up. Finally, there must be a clear way to measure progress. Learning how to play the guitar allows you to listen to your own improvement and enter flow but if you practiced guitar with noise canceling headphones, you likely will drop the new hobby. Video games are the best example of modern flow states. The best selling and most addicting video games integrate these 3 characteristics well. The player is usually motivated and focused on the game in the beginning. They start at a beginner skill level and the game scales up the difficulty as your skill improves. Note how games that are too easy or too hard end up as bad games. And finally, they give you feedback of your progress when you win or lose.

If you can integrate these 3 requirements into your work or hobby, you will become happier.