Temptation bundling is a self-enforced technique that combines something you want to do with something you find hard to do.
If you find it hard to work out at the gym, you can make it more appealing by only watching your favourite shows when you're there. If you struggle to get down to working on a project, combine it with the only time you order your favourite drink. The hope is that the treat is enough to get you stuck into the hard task.
Temptation bundling is a kind of commitment device like that used by Odysseus.
Temptation bundling is from Katy Milkman, who also taught me about the Fresh start effect, and has a book called How to Change. It's also one of the techniques discussed in James Clear's Atomic Habits.
For a study evaluating temptation bundling, see: Holding the Hunger Games Hostage at the Gym: An Evaluation of Temptation Bundling, Milkman et al., Management Science, 2014