A new idea can make the work feel obvious before the assumptions have been tested. That energy is useful. The mistake is using the strength of your enthusiasm as proof that other people have the same problem or want the same solution.
Write the uncertain part
List what would have to be true for the idea to work. Someone experiences the problem frequently. The current workaround is costly. They can adopt an alternative. They are willing and able to pay for it. Each statement needs different evidence.
A friend liking the concept may support none of those assumptions. A potential customer showing you a recurring problem is more informative, even if they are less enthusiastic about your proposed solution.
Spend energy on contact with reality
Use the initial motivation to arrange interviews, build a small demonstration or test a manual version. Avoid investing all of it in branding and infrastructure before learning whether the central problem matters.
Give the test a decision rule. What response would justify another week of work? What result would make you change the approach? Agree on this before seeing the results.
Keep a separate idea list
New ideas often become attractive when the current project reaches an uncomfortable stage. Saving the idea lets you revisit it without abandoning an existing commitment every time novelty appears.
Reassess after the first friction
The first obstacle reveals whether the idea is still worth pursuing when it is no longer effortless to imagine. Use both the evidence and your capacity to continue. Excitement can start the investigation; it should not be asked to finish it.