There's more to retirement planning than numbers. Given the fact that many people will be retired for as many years as they were working, it makes sense to really put some thought into what form your ideal retirement years will take.

Glen Ruffenach, author of The Wall Street Journal Complete Retirement Guidebook has outlined three fundamental pieces required for a successful and engaging retirement:

• Good health

• Focused purpose

• Good financial plan

I've worked with a lot of retirees throughout the past few decades, and from what I've seen, Glen's formula may not be all-inclusive, but it is a great start.

Good Health

Without health, the dollars and cents won’t mean as much. Many diseases and physical ailments seem to be the luck of the draw and often inexplicably strike the fittest among us. However, dedicating time, effort, and some of your budget toward health and fitness can help you have the best shot at being able to fully enjoy the fruits of your working years. In my case, I’ve added yoga to my exercise routine with a specific goal of maintaining flexibility, range of motion, and balance as I age.

Focused Purpose

Family and career are often the primary purposes in people’s lives pre-retirement. What is going to be your reason to get up and get moving once you’ve retired? What will give you a sense of accomplishment, meaning, and purpose? Family is still high on many retirees’ lists, but I also see retired clients building homes for Habitat for Humanity, as well as volunteering with museums, homeless shelters, and police departments, while other people use their career leadership skills to help the Boy Scouts or their churches or to serve on boards. Believe it or not, there are even some people who retire, find they miss working, and get a job!

Good Financial Plan

A good financial plan is a mission I’ve built my career around! The idea that clear goals, discipline, and sound strategy can help a person to design their desired financial future is something I’m completely in favor of helping bring to fruition for all my clients!

The Missing Element?

But what if Ruffenach is missing key elements for a successful retirement? What if he’s spot on? Do you need top marks on each of his prescribed pieces to really achieve a successful and engaging retirement?

Some retirees wish they had better health and the bodies of their youth, but they still enjoy the freedom they have to spend time on hobbies and passions that they can choose.

Having a focused purpose can clearly bring drive and energy, but I suspect the importance of identifying a named purpose(s) in retirement varies from person to person. After all, I know many people who are still working and don’t seem to have any grand purpose in mind, other than to live their lives and enjoy special moments.

A good financial plan? I have friends who seem to be quite happily retired with only a small amount of savings and living off their social security checks—as long as champagne tastes haven’t forced them into beer budgets due to poor planning!

So, is there a must-have key to a successful retirement? As I’ve thought about Ruffenach’s “Engaging Retirement” list, one key item stands out to me as missing: quality relationships. Sure, there are some lone wolves out there who don’t mind a solitary existence, but when I ask retirees visiting my office what they’ve been up to, the first stories they tell are almost always about time spent with friends and family. With that in mind, as you focus on investing your finances for the long-term, remember to also focus on investing in your relationships for the long-term.