There are more jobs available for retirees than being a greeter at Walmart.

Open-minded people can take advantage of many fun, offbeat, and interesting jobs that can help keep them active and engaged in their later years. Some jobs may even lead to second careers. And going back to work is increasingly popular among retirees. A 2017 survey from the RAND Corporation found that nearly 40% of American workers over the age of 65 had previously retired at some point.

Whether you're returning to work out of financial necessity or because you're bored and in need of social interaction and mental stimulation, here are five fun jobs that can help keep you young at heart.

A golf ball near a hole

Golf course marshal is just one of the many interesting jobs available to retirees looking to return to the workforce. Image source: Getty Images.

1. Cruise ship lecturer

Do you love to travel? Enjoy meeting new people? Like to go down south where it's warm during the winter? If yes, then you should consider becoming a lecturer on a cruise ship. Many of the top-rated cruise lines employ older and experienced people to provide lectures on a wide range of subjects, such as the history of a particular destination, food and wine, photography, marine life, and lighthouses. These seminars are meant to educate and entertain guests. So if there's a subject you're an expert on, you may be able to parlay that expertise into a job that pays fairly well and offers free accommodations and travel.

Many cruise lines also hire older people to teach dance classes, work in gift shops, or take photographs. Most jobs aboard a cruise ship pay between $1,200 and $1,500 a month, plus free room and board. However, most cruise ship workers also get tips, and as expenses are kept to a minimum, it's easy to bank most of the money earned.

2. Dog walker

If you go for a walk every day and enjoy being active, you should give serious thought to becoming a paid dog-walker. This is a job tailor-made for retirees. It requires availability during the day (when most dog owners are at work), a love of the outdoors, a good deal of free time, and patience. (Caution: It's not for people who dislike animals or have allergies.)

According to jobs website Indeed.com, dog walkers in the U.S. charge an average of $15.62 an hour per dog. Get three dogs to walk at the same time, and you could earn $47 an hour for taking a walk that you would take anyway. Some dog walkers charge between $25 and $30 an hour per animal, depending on their experience and the distance they walk.

Becoming a dog walker can be as easy as canvassing your local neighborhood. You can post signs at local parks or community mailboxes advertising your services, or you can rely on social media -- from creating a Facebook page to posting your name and contact information on websites such as Rover.com. Once you get a reputation for being a reliable dog walker, it won't take long for word to spread and for you to establish a clientele of pooches. 

3. Baseball park attendant

Why greet people at Walmart when you can take their tickets and greet them at the ball park? Most professional baseball stadiums across the U.S. hire hundreds of seasonal workers during the spring and summer months -- many of them seniors. From directing traffic in the parking lot to taking tickets, showing people to their seats, and handing out programs, there are plenty of jobs to be had at ball parks.

While this is seasonal work and most positions pay minimum wage, these are great jobs for people who enjoy being active and social -- and who want to be at the ball park during the summer as their team chases a pennant. Some baseball teams even hire older people just to engage with fans and children.

4. Golf course marshal

Another great way to enjoy the summer, stay active, and socialize is to work as a golf course marshal. This is actually a pretty serious position. Traveling around in a golf cart, the marshals -- or rangers, as they're sometimes called -- ensure the pace of play around the course continues in a steady and orderly fashion. They may ask some golfers to speed up and ask others to slow down. Marshals also answer questions, enforce course policies, direct traffic, mediate disputes, and help people search for missing golf balls.

According to website SimplyHired, golf course marshals at exclusive courses, as well as those played by professional golfers, earn an average of $70,000 per year. At most local public golf courses, the role of course marshal is staffed by volunteers. However, even volunteer marshals get free golf in return for their hard work. And for many golf enthusiasts, free play is all the compensation they need.

sommelier filling three wine glasses with white wine

Image source: Getty Images.

5. Wine taster

Do you have a taste for the finer things in life? Know a lot about wine? If yes, then you should consider becoming a professional wine taster in retirement. Also known as sommeliers, professional wine tasters are in demand by restaurants, bars, wineries, and some liquor stores. The role involves everything from tasting different wines and suggesting pairings of wine and food to developing wine lists and training restaurant staff about the many subtleties of wine -- the difference between a merlot and a pinot noir, for example. Some sommeliers also give lectures and seminars about wine to the public, in settings ranging from church basements to community college night classes.

Becoming a professional wine taster does require training and certification. There are several schools in the U.S., such as the Napa Valley Wine Academy and the Wine School of Philadelphia, as well as many certification bodies around the world. You can find information on courses and how to become a certified sommelier on the website SOMM ("Sommelier Trade Review"), which provides professional reviews of all the major U.S. wine schools and certification bodies, as well as information on their programs. Becoming certified can take as long as two years, but if you truly love wine, the investment of time may be worth it. According to GuildSomm (the Guild of Sommeliers) in Petaluma, California, salaries for sommeliers range from $75,000 to $150,000 depending on their level of certification and where they work.

As you can see, there are many job options for retirees. Other interesting jobs you may want to consider include park ranger, tutor, school bus driver, museum guide, amusement-park attendant, Uber or Lyft driver, and pet sitter. When it comes to re-entering the workforce, you're only limited by your imagination.