If your first target disappears, then find a second and follow them.
Spend at least half a day on this, preferably longer. Commit yourself to take buses, trains, etc. whatever is necessary in order to follow your ‘target.’
Real, oppressive stalking is fueled by an intense obsession; here there is no obsession, there is only submission to the other. This should dissipate any intensity. This liberation is what you should aim to express.