Put your own money on the line to make yourself follow through, but first ask whether you would be willing to

Moderate value
Evidence A
Saves time
Costs a little
Takes minutes
Some willpower

In plain words

To push yourself to follow through, you can get a bonus when you do it, or you can pay a deposit up front that is returned, with a bonus added, if you do it. Among people willing to join either kind, the deposit group followed through 13 percentage points more. But only 13.7% were willing to pay a deposit, against 90% willing to take a bonus, so a deposit only helps the people who are willing to put one down.

Cost: A deposit-style plan requires you to put up some of your own money first, which is forfeited if you don't follow through. The trial used 150 USD.
What you get: In a randomized trial of 2538 people in the United States, employees and their relatives and friends were randomly assigned to one of four incentive plans or usual care. The reward plan (about 800 USD for succeeding) was accepted by 90.0%, and the deposit plan (pay 150 USD up front, plus a 650 USD reward) by 13.7%. For smoking abstinence sustained over six months, the four incentive plans ranged from 9.4% to 16.0%, and usual care was 6.0%. The reward plan was 15.7% and the deposit plan 10.2%. But among only the 13.7% of people willing to join either kind, the six-month quit rate of the deposit plan was 13.2 percentage points higher than that of the reward plan (95% CI 3.1 to 22.8, the plausible range).
Notes: This trial measured quitting smoking. Carrying it over to things like writing a thesis or working out is a step by extension, so the size of the benefit is rated "medium." When choosing a plan, first look at whether you would really use it. A method most people won't accept does nothing for those people, however strong its effect. So pick the kind you are willing to accept first; even a small deposit is better than none. For how to quit smoking itself, see §2.3 (quit-smoking medicines).
Evidence grade: A : Specific numbers from meta-analyses, large cohorts or randomized trials; for law and policy, the statute or official text.
Sources: Halpern SD, French B, Small DS, et al. (2015). Randomized trial of four financial-incentive programs for smoking cessation. New England Journal of Medicine, 372(22), 2108–2117. https://doi.org/10.1056/NEJMoa1414293

Translated from the Chinese original. Original book, section 4, tip 11. Content may be out of date and rules differ by place. When you actually deal with an agency, a doctor or a court, follow what local officials, doctors and lawyers tell you. Disclaimer