Create choices
Let's say I knew I wanted to exercise but I always put it off. What if there was a choice task. Appears like a normal task. One task might be: do nothing. Another might be go for run for 1 hour. Another might be go for run for 2 hours.
Now if we could see that 2 hours would give us way more benefits then I believe we would choose option 3 over the other choices.
So originally appears 3 choices, I select one. I'm presented with a new task that dependant on me selecting that option. Now the previous 2 choices are now gone.
If I had of chosen one of the other choices then a different task might had appeared