I see the first hour of work in any given day as a way of maintaining the project and making minimal progress. Anything after that is the "bonus," where the progress will be substantial. So if I am able to work an hour, that's great. An hour and 45 minutes is like an hour of maintenance and 45 minutes at time-and-a-half. This method allows me to snatch significant moment throughout a busy day just to get up to my hour, and then everything else is just extra.
Progress will seem slow when judged by hours and days, but rapid when judged by months and years.
Words have a power of their own. For example, I found myself using the ridiculous phrase "iron will" about myself, as in "I have an iron will." Obviously I don't, and the phrase sounds silly. Yet somehow that phrase worked for me and allowed me to persevere on a day when it seemed otherwise unlikely that I would do so. Some people derive power out of affirmations of weakness, abjectness, and powerlessness, I've never understood it, but there you go. If that works for you, go for it.