Hooked By Nir Eyal mentions of a 4 step Hook Model in order to create “habit forming” products. The steps are as follows:

1. Trigger – Internal teiggers followed by external triggers to cause a craving
2. Action – Take action after getting enticed by the trigger
3. Variable rewards – These make dopamine to flow through our veins and get us excited
4. Invest – Invest once convinced with the rewards