Nostalgia is memory with the bad parts cropped out. Don’t judge your now against a cropped then.

Memory edits, and it edits toward pleasantness. Last summer comes back as three good afternoons with the boredom, the arguments and the long empty stretches cut out, and then you set today against that, unedited, with all its dullness attached. The comparison was rigged before you started.

When a stretch of the past starts to glow, deliberately recall the boring parts of it. What were you worried about then, what did you complain about, how many of those days were nothing much? It does not spoil the memory, and it stops you concluding that your life has gone downhill since you were fourteen.