Thats the great thing about Exchange Traded funds which track an index - there's no thinking to do just invest in the fund for example this is a popular one: Vanguard S&P 500 ETF (VOO)

And when you buy this you are effectively buying, Apple, Amazon, Google, Johnson & Johnson, Procter & Gamble Co, NVIDIA etc because the fund will go ahead and buy all the largest 500 US companies weighted by market cap.

The S&P500 has returned an average of 12% a year for the last 10 years.