What did you expect it to fix?
Keep the season
Suppose the next thing passed the test and you did it. Or suppose you did one years ago, and you're now in the house or the job or the relationship and the season has long since worn off. This chapter is about the two things the research suggests slow the wearing off, and neither is a new purchase.
Sheldon and Lyubomirsky's model from chapter 17 named two moderators, two things that stood between a good change and the erosion of its gains. The first was continued appreciation of the original change. The second was continued variety in the experiences the change made possible. In their three-month study of students who'd had a positive change, both slowed the two routes of erosion. The gains lasted longer for people who kept noticing the thing, and for people who kept doing different things with it.
Keep noticing. This is not gratitude as an instruction, which I find useless and which an earlier book in this series, Thank them now, had its own reasons for handling carefully. It's narrower and more mechanical. The coat in chapter 7 stopped being noticed because it was worn the same way every day. The house stops being noticed for the same reason. Appreciation, in the sense Sheldon and Lyubomirsky meant it, is deliberately returning attention to the thing that changed, and it can be done once a week in a sentence. On a Thursday, at four, say what's different because of the change. "I'm home already." "There's no shouting in this office." If the sentence has a fact in it, the change was a fix and the noticing keeps the fix in view. If the sentence has nothing in it, the change was a hope and you've learned something cheaply.
Keep varying. The second moderator is about what you do with the thing. A garden used the same way every weekend becomes the wall outside the window. A garden in which something different is tried, a thing planted, a table moved, a person invited, stays a garden. A new job in which the work is the same by the third month is the old job with a different logo. A new job in which you take the odd task, sit with a different team, learn the thing nobody else wants to learn, keeps being new for longer, and the research suggests the newness is what the season was made of.
Notice that neither of these is available from the sofa. Both are things you do to the life in hand, whether it arrived last month or ten years ago. Which is the point. The season isn't a property of getting the thing. It's a property of how the thing is held, and a thing held with attention and used in varied ways keeps more of its season than a thing acquired and left to become ordinary. That's the closest the research comes to telling you how to make a next thing last, and it turns out to be advice about Thursdays.