Received a windfall? Here is what to do next.

What if overnight, your financial situation meaningfully changed? For some of us, this can and does happen, whether due to an inheritance, a generous gift or a successful investment. When cash like that hits your bank account, it can be hard to stop and think — but it is essential that you do.

While you may assume it’ll be smooth sailing ahead, a “sudden influx of assets can lead to missteps that could undermine your good fortune,” said Fidelity, citing Terri Lyders, the vice president of advanced planning for Fidelity Investments.