While many young Americans might be statistically behind on retirement planning, the good news is that people under the age of 30 still have a lot of time to catch up. Time is the friend of a long-term investor, and Americans in their 20s still have plenty of it.

Even starting with no savings, if you saved $500 per month at a 10% annual return (the average market return over the last century), your stocks would be worth $8.6 million in 50 years. Doubling your monthly savings or slightly increasing the rate of return would increase that amount substantially.

If you're already maximizing your retirement savings and want to outperform the average market return to hit your financial goals sooner, it can be done with the right growth stocks. The key is to invest your money in established companies that are demonstrating leadership in their respective markets and have already been growing for several years. These winners can usually be found among the brands and services you use every day.

Here's a look at three outstanding companies that have strung together several years of above-average growth as they've benefited from promising megatrends in artificial intelligence, athletic apparel, and e-commerce. They should be surefire bets for outperformance over the long term.

1. Microsoft

You can get off to a good start by buying shares of Microsoft (MSFT 1.82%). The reason is simple: artificial intelligence (AI) is one of the biggest growth opportunities of our time, and it positions the software giant for profitable growth over the long term. It's also drowning in cash, giving it ample resources to invest in cutting-edge technologies.

Microsoft generated $63 billion of free cash flow -- a key measure of a company's profitability -- on $218 billion of revenue over the last year.

Revenue grew 13% year over year in the most recent quarter, but Microsoft's cloud computing business, which is starting to benefit from growing demand for AI services, continues to be the standout, generating $31.8 billion in revenue last quarter, up 24% year over year.

"We are rapidly infusing AI across every layer of the tech stack and for every role and business process to drive productivity gains for our customers," CEO Satya Nadella said.

While companies will increasingly turn to Microsoft's cloud solutions, Microsoft Copilot and the new AI-powered Bing search feature should see growing demand on the consumer side. Microsoft is charging $30 per month, per user for Copilot, which brings generative AI tools to Word, Excel, and other Microsoft 365 applications.

Over the last 10 years, Microsoft's total revenue grew 10.5% per year, with higher margins increasing profits, or earnings per share, by 14%. AI services should drive more demand for Microsoft's core software products, Windows, and the Azure enterprise cloud service business, leading to solid returns for retirement savers.

2. Lululemon Athletica

Another growing market that is a safe bet for the long haul is athletic apparel. This has been a steadily growing segment of the apparel industry for many years. Nike is the leader with $51 billion in annual revenue, but Lululemon Athletica (LULU 1.31%) seems to be the next global athletic brand in the making. With $9 billion in annual revenue, it has a long way to go to catch Nike, but its record of growth looks promising.

Lululemon shares are up around 725% since 2013. Revenue is on pace to grow 18% this year, and there's still a tremendous opportunity ahead.

Lululemon is differentiating its brand by capturing two powerful trends. It serves consumers looking for premium workout gear, while also offering an assortment that meets the growing demand for comfortable wear suitable for the office.

The result is 19.5% annual revenue growth over the last decade. Management is guiding for about 15% annualized growth through 2026.It will likely keep growing at double-digit rates well beyond 2026.

Lululemon is still in the early stages of expanding in emerging markets. It grew international revenue by a whopping 49% year over year last quarter, and is still showing double-digit growth in North America.

Lululemon has been on an upward trajectory since its founding more than 20 years ago. However, in 2022 management estimated its market share at only 1% of its total addressable market of $650 billion. If you're interested in simple stocks that can beat the market, Lululemon is a good candidate.

3. Shopify

It's smart to think about ways AI will benefit the economy, and which stocks will benefit. A promising market to consider is the $5 trillion e-commerce market, and one of the top stocks to consider here is Shopify (SHOP 1.11%).

Shopify provides software tools to help businesses of all sizes launch online storefronts, manage sales, and make payments, among many other capabilities. From 2017 through 2022, the company grew revenue from $673 million to $5.6 billion.

An important quality of Shopify's business is that it generates recurring revenue from subscriptions, but it also shares in merchants' success by earning a percentage of payment processing fees, shipping labels, and other transaction services. Merchant services revenue grew 24% year over year in the third quarter and made up 70% of the business.

Shopify has a long runway of growth. E-commerce has been gaining share of total retail spending for 20 years, but it still represents less than 15% of consumer spending in the U.S. New technologies like virtual try-on services powered by AI will serve as catalysts for the e-commerce market.

Shopify is already investing in AI to stimulate demand for its platform. It recently launched Shopify Magic, which is an assistant that integrates with merchants' data and speeds up productivity in areas like marketing and customer support, among other tasks.

Shopify is the operating system for business, with major tailwinds behind it. It only has a 10% share of U.S. e-commerce spending, but it's also operating in a growing e-commerce market that should deliver market-beating returns for a long time.