In other words, happy people make successful lives, and not the other way around. That means, if your general philosophy on life is that you set about achieving things, because that is more important than happiness, then your approach is flawed. Because happy people make more success.
By the same token, if your general “plan” follows the logic of “I’ll be happy when I have achieved [some goal or objective]” then your plan is flawed. On balance, achievements don’t produce happiness - rather, happiness produces success. Happy people make happy lives.