There's a variety of good reasons to plug into the stock market. For most of us, though, the primary goal is funding a nice retirement. And to reach that goal, we just need plain old growth to turn a little money now into a lot more money later.

That's easier said than done, of course. Sometimes it seems the more often we trade, the more we miss out. Other times our long-term picks just don't pan out. Often times it's a little bit of both.

If you feel like you're just not making enough progress toward building your nest egg, maybe it's time to adjust your approach. Rather than hunting for the market's buried treasure and selling it when it looks like it's raced too high, why not step into some less flashy and more established names with clear growth prospects, and then just sit on them for a few years?

Here are three such stocks that can help lead you to a better -- and bigger -- retirement fund.

An older couple sitting on porch steps.

Image source: Getty Images.

1. Apple

It seems a bit of a cliche to own a piece of what's not only the world's biggest company but also the world's most recognized brand name. What makes both of those things true, however, is also what makes Apple (AAPL -2.22%) a great long-term growth holding.

There was a time when the company's continued growth was in question. More than half of its business in recent years has been driven by sales of its iPhone, which is impressive, but also dangerous. What happens when everyone who wants an iPhone owns one and then isn't stoked to upgrade it?

Upon closer inspection, though, we see there's still tremendous room to expand.

CEO Tim Cook told Reuters earlier this year there are now over 1 billion actively used iPhones, accounting for the lion's share of the world's actively used 1.65 billion iOS devices. That only accounts for a fourth of the world's mobile-device market share, according to Global Stats. Moreover, while 1 billion is a big number, it's only a fraction of the global population of nearly 8 billion, and less than a third of the world's roughly 4 billion smartphones in current use.

Then there is the company's relatively young services business, driving revenue via sales of digital apps and subscriptions. While last quarter's services revenue grew 27% to a record-breaking $16.9 billion, that still translates into quarterly revenue of less than $17 per iPhone user. The company should seemingly be able to extract more. As time marches on and Apple gets better on this front, the sky's the limit for this piece of the company's business.

The point being, Apple's still got lots of low-hanging fruit left to pick.

2. PayPal Holdings

Plenty of newcomers like Square and Adyen are taking aim at PayPal Holdings (PYPL 0.92%), to be sure, and even gaining respectable traction. But the original digital payment middleman is still the big bully within the business, and remains one of the top investment prospects within the industry.

Even now, more than a year removed from the surge in online shopping stemming from the pandemic, PayPal's growth continues to accelerate. For the quarter ending just this March, total volume of payments facilitated was up 46% after stripping out the impact of changing currency values, while revenue improved by 29%. Considerably more scale led to incredibly better profits, with operating and per-share income improving 84% year over year. Perhaps the most curious of PayPal's first-quarter metrics is the net addition of 14.5 million new users, bringing its user head count to 392 million.

These are all big numbers, but PayPal's reach is still relatively modest in comparison to the worldwide digital-wallet market -- a market that Juniper Research estimates will swell from $5.5 trillion worth of payments in 2020 to $10 trillion by 2025.

And the company is certainly moving wisely to win its piece of this market that's up for grabs. Earlier this month, PayPal announced it would acquire Happy Returns, which simplifies returning unwanted items purchased online. Early last year, PayPal acquired Honey, steering online shoppers to the web's best prices on any particular item. And CEO Dan Schulman said just a few days ago that he envisions a PayPal that offers savings accounts, check-cashing services, and even stock trading.

It remains to be seen if all these plans (and others) will pan out. The company's certainly entering into these growth initiatives with a well-recognized brand name, though.

3. Amgen

Finally, add Amgen (AMGN 1.16%) to your list of stocks to buy to secure a better retirement.

You can find more powerful growth engines. Those other stocks come pre-packaged with a downside, though: Most of them are overly reliant on a relatively small number of drugs, presenting problems when those therapies lose their patent protection or are topped by a more effective alternative.

But not Amgen. Its best-selling drug, Enbrel, still only accounts for about a fifth of its total business, and aside from that rheumatoid arthritis treatment, no one drug accounts for more than roughly 10% of its annual sales. This well-diversified portfolio is one of the key reasons Amgen is far more likely than not to report sales and earnings growth even if that growth isn't exactly thrilling.

This isn't to suggest Amgen can simply coast. It can't. Although Novartis' Sandoz division has been effectively barred from selling a generic version of Enbrel until 2029, it's still coming sooner or later, as are competitors to the other 20 therapies in Amgen's pipeline. The patent and R&D race never really ends.

Amgen is as much predator as it is prey, however. A few dozen drugs are being scrutinized across several different trials underway right now, along with trials of biosimilars of Stelara, Eylea, and Soliris, which treat gastrointestinal conditions, macular degeneration, and neuromyelitis optica spectrum disorder, respectively. Each of these so-called "biologics" is already producing more than $5 billion in annual sales in their branded forms.

This robust pipeline is a function of Amgen's size and the persistent profitability of its portfolio -- the company reported nearly $10 billion worth of free cash flow for fiscal 2020. This cash flow, in turn, ensures the pipeline remains loaded with solid drug prospects, keeping the growth cycle in perpetual motion. Case(s) in point: The pharma company completed its purchase of Five Prime just last month, and is moving forward with its acquisition of Rodeo Therapeutics. The former brings a new gastric cancer treatment into the fold, while the latter will bolster the company's anti-inflammation portfolio.