To ride the wave / go with the flow; to be in good form or take advantage of momentum or current trends.
チームは連勝中で、今は完全に波に乗っている。
The team is on a winning streak and is completely riding the wave right now.
新しい流行にうまく波に乗れば、売り上げは伸びるだろう。
If you manage to ride the trend successfully, sales will likely increase.
彼は最近作品が注目されて、作家として波に乗り始めた。
His works have been getting attention lately, and he's starting to hit his stride as a writer.