Growth isn't that hard to find on the stock market. Many companies easily post impressive sales numbers for a few quarters or even years, especially during booming economic growth periods like investors have seen so far in 2021. When the S&P 500 is up over 20%, it's not unusual for individual stocks to be up 40% or more this year.

But life-changing shareholder returns come from a much smaller proportion of businesses. These are the stocks that can outperform over much longer periods. Companies in this club also tend to do well even during the inevitable downturns that are sure to pressure sales and profits.

So let's take a look at two stocks that seem to have that special growth quality that implies long-term growth that isn't dependent on unusually favorable selling conditions. Read on for some reasons to believe Lululemon Athletica (NASDAQ:LULU) and Tractor Supply (NASDAQ:TSCO) will still be generating great returns for investors a decade from now.

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1. lululemon athletica

Lululemon was an impressive growth business before the pandemic struck. The athleisure apparel specialist had been steadily winning market share in its niche through 2019. Profitability expanded for years heading into 2020 thanks to a streak of popular apparel introductions and a world-class e-commerce selling platform.

Pandemic demand shifts only made those competitive assets more valuable. Lululemon's sales gains accelerated to 28% on a two-year basis, the company revealed in early September. And gross profit margin crossed into record territory as shoppers bought all of its newest premium products.

LULU Gross Profit Margin Chart

LULU Gross Profit Margin data by YCharts

The company still has plenty of room to grow as it expands into new geographies, new product categories, and different demographics. It recently made progress in sports bras, for example, and is finding it easy to market outerwear and menswear.

Management in early 2022 will likely boost their big-picture growth goals given that the chain is hitting many of its 2023 targets several years early. Sure, the apparel market isn't immune from downturns or cost challenges. But lululemon's focus on the athleisure niche should help it outperform through a wide range of selling conditions.

2. Tractor Supply

Tractor Supply shares have more than doubled the wider market's year-to-date return here in late 2021. There's more where that came from, though.

The rural lifestyle retailer is having no trouble maintaining engagement with the millions of new customers it found during the pandemic. Sales jumped 13% last quarter, even following the 27% surge a year earlier. Whether it's home gardening, pet food, or livestock, the chain is thrilling shoppers by stocking the right products with the right ordering and delivery options.

CEO Hal Lawton and his team believe these demand changes are structural, meaning they'll stick around long after the COVID-19 pandemic threat has faded. But you don't have to believe in a decade of uninterrupted industry growth to like Tractor Supply stock today.

The business is surging toward a double-digit profit margin in 2021 while notching a second-straight year of over $1 billion of operating cash flow. Those improving finances should support a big boost to its dividend in early 2022, while also powering more investments in the business operations to protect the chain's new market share.

That's a recipe for continued market-thumping returns from this top growth stock in the years ahead.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.