Full credit for this solution goes to
Gerbasgamer & if he (she?) wants to make their own solution I'll delete this.
Though the description says: "Make someone Happy within the first 60 seconds of a chapter" thanks to Gerbasgamer's comment on the other guide we now know that it also reset the 60secs when you start from a reload, something I felt was so helpful that it needed its own guide.
Short & simplified solution, this can be very easily done in Chapter 1 as soon as you reach Miles, the guy playing trumpet, possess him, quit to main menu, continue game & then use Miles' trumpet to make another one happy by playing to them.
Detailed solution;Again, this can be very easily done in Chapter 1 as soon as you reach Miles, the guy playing trumpet, press
to possess him & move him close to the ice cream guy (he's normally below the elevator) unpossess him & then simply quit out to the main menu & press continue game, once you're back in the game you might not spawn next to Miles in which case press
to bring up the map, find Miles (Bald guy blowing trumpet) press
to teleport to him, repossess him then go to nearest person (should be ice cream guy but they sometimes goes wandering) once next to another person use Miles' trumpet
+ right stick aimed at the other person (aka ice cream man) once a heart pop above their head they are happy & the achievement pop unless you've used 45 seconds reading this while the game was still running lol.
Pro tip: This could be done while doing the "Marching Band" challenge that requires 3 people made happy by Miles at the same time