Writing a book is a long journey.

It takes time, focus, and emotional energy, so choosing a topic you genuinely care about isn’t just nice, it’s necessary.

Readers can always feel the difference between a book written out of obligation, commercial interest, self-promotion, and one written with genuine enthusiasm and authentic desire to help them solve their problems or achieve their goals. 

When you write about something you love, the motivation to keep going stays strong even when the process becomes challenging.

Start with reflection.

Think about your professional life: what do you talk about most passionately? When a friend or client asks you about your work, what makes your eyes light up?

Maybe it’s helping couples rebuild trust, teaching small business owners how to grow without burnout, or showing people how to eat well while living on a budget. Those sparks of passion reveal the subjects that mean the most to you.

Passion, however, needs purpose. Not every topic you enjoy will make a good book. The strongest topics are where your personal excitement meets your reader’s need. For example, you might love discussing the psychology of success, but unless you connect it to a reader’s specific goal like achieving financial stability or breaking bad habits it won’t hold their attention.

To find that sweet spot, take out a piece of paper and draw two circles. In one, list topics that fascinate you and that you could happily research or talk about for months. In the other, list the biggest problems or goals your audience has. The overlap between the two circles is your ideal book topic.

Here are a few guiding questions to help you find it:

Which topics do I never tire of exploring, even on my days off?

What do I feel strongly about teaching, fixing, or improving in my field?

What do I wish everyone knew before coming to me for help?

What wrong assumptions do people have that I’m eager to correct?

What have I personally experienced that could guide others?

Once you have several ideas, test them. Talk about each topic casually with clients, colleagues, or friends. Notice which ones make people lean in, ask follow-up questions, or say, “I’d read a book about that.” You can also post short snippets or polls online to see what sparks engagement.

Market research doesn’t have to be complicated; it’s simply listening for enthusiasm.

When you’ve narrowed your ideas, consider your stamina for each topic. Some subjects sound exciting for a blog post but lose appeal after three chapters. Others grow richer the more you explore them.

Ask yourself honestly, “Could I spend the next six months immersed in this topic and still find it fascinating?” If the answer is yes, you’ve likely found your winner.

Also think about longevity. Will your chosen topic still be relevant a few years from now? Evergreen topics (those that address lasting human needs like relationships, health, mindset, or success) tend to have the longest shelf life and strongest book sales over time.

Finally, check that your topic aligns with your professional goals. If you’re a coach, therapist, or consultant, your book can serve as a powerful introduction to your services. It can attract your ideal clients by demonstrating your expertise.

If you’re in a corporate or academic field, it can strengthen your reputation and open doors to speaking, media, or teaching opportunities. A book that’s both personally fulfilling and professionally strategic gives you the best of both worlds.

Your Assignment:

• Write a list of ten topics that excite you.
• Write another list of ten challenges your readers or clients face.
• Find where those lists intersect. Choose three possible book ideas from that overlap.
• For each idea, write one sentence that completes this thought: My reader will finish this book knowing how to…

The topic that feels most energizing and meaningful will likely be the one that carries you through the entire writing process. When you love what you’re teaching, your readers will feel it, and that’s what makes a book unforgettable.