virtuous cycle; upward spiral
A self-reinforcing positive feedback loop where good outcomes lead to further good outcomes. Often contrasted with 負のスパイラル (vicious cycle).
Antonyms: 負のスパイラル
After I started exercising, I got healthier and began to enjoy it more, entering a virtuous cycle.
A virtuous cycle is expected, where economic recovery encourages spending, which in turn further improves the economy.