The Flywheel Effect is used to describe a handful of concepts at once, which are rarely split apart:

• Momentum: Flywheels are hard to get moving. If they get moving, they are likely to continue.
• Feedback Loops: The faster the wheel is spinning, the easier it is to add incremental speed. 
• Compounding Return on Effort: Continuous small inputs add up into an impressive output, eventually.
• Direction: Sustained effort must be focused in one direction in order to maintain momentum and compounding returns. 

Flywheel Effect: Positive feedback loops that build momentum, increasing the payoff of incremental effort.

When good things you do lead to more good things “just happening”.