Mental contrasting is essentially contrasting your happy, dream goal with your current reality, emphasizing the need for action, while implementation intentions are "if-then" statements about how you will deal with obstacles. The link goes to a journal article in which this combined technique was used to help women become more physically active, and the effect was sustained over months.
Great example of sales/marketing methods to learn from
In general, “you’re 10 to 15 times as likely to buy something your friends bought because you have the same inherent preferences, and twice as likely because your friends influenced you,” Aral says. However, the level of peer influence varies by how connected the people are— fellow alumni exert more influence over one another than neighbors—and whether or not the message is personal.
Incentivizing positive behavior change
"Perhaps the most powerful influence on human behaviour is other people."