The whims of the market make forecasts a fool's errand. The only thing that any investor can reasonably predict about the stock market is that it's unpredictable. That means market-timing strategies are often unprofitable and unsuccessful.

Consistently putting your investment capital to work with a long-term mindset that ignores the market environment is a much simpler (and more successful) strategy. Any stocks you buy should fit in with your portfolio goals and risk profile, and you should know the companies well. Staying in the market can mean being invested on its worst days, but you're also there to benefit from the best ones. 

If you're looking for companies worthy of putting cash into and holding in your portfolio for years, here are two high-growth names to consider. 

1. Intuitive Surgical 

Intuitive Surgical (ISRG -0.02%) stock trades down about 11% over the past year and about 30% from its January 2022 all-time highs, despite its continued steady revenue growth and profitability. The macroeconomic factors afflicting growth stocks are a factor here, including fluctuating investor sentiment. But the company also experienced a lag in procedure volumes during periods of COVID-19 resurgences in certain markets last year that spooked investors. 

But there is a lot of quality to be found in Intuitive Surgical's underlying business, which develops, manufactures, and markets robotic products used in minimally invasive surgery (most notably its da Vinci Surgical System). The company continues to grow its installed base of systems -- a key determinant of its recurring streams of revenue -- and growth remains particularly strong, compared to pre-pandemic levels.

Although many surgical procedures were delayed earlier last year in key markets like Europe and Asia due to COVID-19 case spikes, the types of procedures that Intuitive Surgical's products support are generally not elective. For the procedures that are elective, the company will soon get past any unfavorable year-over-year comparisons from pandemic-affected quarters.

Case in point: The company ended 2022 with 7,544 da Vinci Surgical Systems installed worldwide. This was 12% more than it had installed at the end of 2021 and 35% higher than its installed base of systems at the end of 2019.

Intuitive Surgical reported revenue of $6.2 billion and earnings of $1.3 billion in 2022. That top-line figure was up 38% on a three-year basis.

While the company can make millions of dollars from just one sale of any of the latest models of its da Vinci Surgical System, it also earns plenty of revenue and profits from its recurring revenue streams related to its installed base. These are derived from its software support, tech services, instruments, tools, and other accompaniments it sells to the medical providers and hospitals that purchase its surgical systems.  

The multibillion-dollar surgical-robotics market is only growing, and Intuitive Surgical controls more than three-quarters of the revenue generated in this entire global industry. For long-term investors, now could be the time to scoop up this healthcare stock on the dip, as its growth story appears to be far from over.  

2. Innovative Industrial Properties 

Innovative Industrial Properties (IIPR -0.88%) has built a business that continues to buck the trend in the highly volatile marijuana industry. Unlike several other cannabis-related companies, this one has a strong history of growing revenue and profits. A lot of the reason for that is tied to its core business model.

Innovative Industrial Properties is structured as a real estate investment trust (REIT). As of the end of 2022, the company managed a portfolio of 110 properties distributed across 19 states, with 55% of its portfolio rented to public entities and 45% to private ones. No company leases more than 14% of its operating portfolio, and no state accounts for more than 16% of its locations. Innovative Industrial Properties only rents its facilities to state-licensed marijuana operators, with a focus on the medical-use space. Among its tenants, 85% are multi-state operators.

The strength in its business model is that Innovative Industrial Properties' business model is that its tenants operate under triple net leases, with the average lease running 15 years and rent-escalators built-in. Tenants are locked in long-term and most of the property costs (like taxes, maintenance and insurance) fall onto the tenant rather than the REIT. This allows Innovative Industrial Properties to benefit from the growth opportunity of the marijuana industry with far less risk than the actual tenant operator.

Of course, no stock is without risk, and the industry in which Innovative Industrial Properties operates is somewhat speculative at the moment because marijuana is still illegal on a national level. Still, the company's business model and lease structure helped it to grow its revenue, profits, and funds from operations by respective amounts of 1,770%, 2,110%, and 2,140%, over the trailing five years.

It pays a dividend that currently yields about 10%, and that dividend has jumped 70% over the past three years. For income investors looking to gain exposure to the growth potential of the marijuana space, this stock could be a notable contender for a well-diversified basket of long-term holdings.