The three major indexes have all slipped into bear territory in recent times. And many of the strongest stocks have followed. In some cases, these usually solid companies are struggling with today's challenges, such as rising inflation and supply chain problems. In other cases, they're managing headwinds -- but investors still are staying away.

And this means the idea of investing right now seems a bit scary. But scary or not, bear markets are an excellent time to start investing or continue on your investment path. Let's talk about why.

Bear markets don't last forever

First, here's a very important point. Bear markets don't last forever. As my colleague Katie Brockman points out, history shows us the average bear market lasts 388 days. That's about a year. So, if you invest during these difficult times, brighter days generally aren't too far off.

Economic troubles also remain rather limited in time. If we use recessions as an example, history shows they generally last about 10 months. This means brighter days for companies aren't too far off either. Companies with a solid earnings track record, healthy finances, and strong leadership generally can make it through these difficult times -- and thrive when the environment improves.

This tells us that companies we believe in can go on to perform well after economic downturns. And we won't have to wait an incredibly long period of time for stock market performance to improve. Both of these points should help us worry less when we see our favorite stocks tumble during this bear market. And this means we may start to think favorably about the idea of investing.

Why invest now?

But why invest now? Why not wait? Today, many stocks are trading at bargain prices. Certain ones, such as e-commerce giant Amazon (AMZN 0.83%), are struggling with rising costs -- and it's showing in earnings and share price performance.

Others, like home improvement leader Home Depot, are defying the economic downturn. Home Depot reported record earnings in spite of the crisis. Still, though, Home Depot's stock has suffered since the start of the year.

Both stocks offer investors good buying opportunities now that they are trading at lower valuations. And that's because their future prospects remain bright.

These are just two examples. There are many others in similar situations. And one big reason to buy now is that it's impossible to time the market. No one can predict exactly when a stock will hit its absolute lowest point. And if you invest for the long term, it doesn't really matter. By holding for the long term, I mean investing for at least five years.

We can use Amazon as an example again. Over the past decade, the stock has climbed more than 800%. You don't have to buy at the low and sell at the high to win, though, as you can see from the chart below. There are a lot of areas in between that can produce great returns.

AMZN Chart.

AMZN data by YCharts.

So even if you buy a stock today and it retreats further, not to worry. You still may reap big rewards over the long term.

Recovery and growth

And if we invest in a stock during a bear market -- when it's down -- the five-year-or-more time frame allows us to benefit from the company's recovery and the growth that follows.

A bear market also is the perfect time to pick out the strongest companies. It allows us to examine how they're managing the current crisis -- and if they're making smart business decisions.

So, yes, you may be able to pick up a stock cheaper at some future point. But it's probably not worth watching the ticker every minute of every day to try to get that price. And even if you do make that effort, you might not be successful.

Instead, it's best to invest when you consider a particular stock cheap -- or even reasonable -- considering growth prospects. And this bear market is offering us many of those opportunities on a silver platter right now.