The Minimum Viable Product, of course. The least you think your product needs to be understood and convert some users.
Somebody sent me this image this morning and asked my opinion about it.
I don’t get the sad and neutral face to the skateboard, the kick scooter and the bike. Riding any of them can be super fun from the get go. So I’d change the smiley face to super happy from products 1 to 3 as well.
If your MVP meets or even exceeds the expectations of some of your personas, that’s it!, there will be happiness. Just don’t make the mistake to call the skateboard a kind of car minicar… your customers won’t understand you, let alone your product.