My problem with setting a deadline is I'll underestimate the workload and then end up spending the week before pushing myself way too hard to meet it.  This is one reason why most of my goals are now time based. Spend at least 10 dedicated hours per week on X, rather than have X finished by month 2 or else.  Since I've converted to this I'm also much better about giving estimates to clients on when their work will be done and generally I finish things way ahead of schedule because I don't have the opportunity to procrastinate starting. 

Obviously if you're the type of person who puts off shipping something for months because it "has to be perfect" this wouldn't work for you though, but my problem was always prioritizing which project to work on, now that's decided at the begining of the week.

I agree with most of what you say here, Sebastian. However, I think the problem does not lie necessarily with pace, but rather with goals that require a maximum sustainable pace to reach. Not reaching a position-based goal (i.e. "I need to reach this precise destination in X amount of time") can be very demoralizing, but I think that velocity-based goals (based on the pace at which your progress, regardless of goals) are much better to taper motivational troughs. And the good thing about velocity-based goals is that they also allow for inevitable bumps in the road and unforeseeable circumstances where you know you'll have to take a break. I've used this method during the past few months and I've really gotten a lot done (including starting my own blog, learning about basic programming and web design, learning photography, Photoshop, and still going strong with my Chinese studies).  I've actually written a blog post partly on this idea, which I borrowed from Scott Young. Here's the relevant excerpt:

"Scott Young is a popular blogger on learning and productivity, who recently completed his 1 year MIT Challenge. In his free e-book entitled “Get More From Life,” Scott argues that focusing only on how much growth we are experiencing at any given moment is the only true indicator of success. This is because the past has already occurred and only exists as a fuzzy memory. The future hasn’t yet happened and lies only in the realm of speculation.

If you have ever set goals for yourself and have failed to reach them, you probably know that this is usually very demotivating. This is often why so many new goal setters fail to continue with this practice, says Scott. The pain of failing to achieve when you’ve tried your best is often too great. Velocity-based goals remove this problem entirely.

Velocity simply refers to the speed at which you are learning. The goal is, therefore, not necessarily to reach a certain destination in the distant future, but to make sure that every day you cover a distance satisfying enough so that you feel like you are making good progress. Now, take good note of the following: because a goal is simply a servant of directing and pushing your own growth, as long as you know you are trying your best (maximum velocity possible), then the goal is successful regardless of whether you underestimated the deadline necessary.

Nonetheless, position-based goal setting can still be useful, but I would encourage you to combine position-based goals together with velocity-based goals. For example, have a position-based goal where you see yourself at a certain point (destination) in the future (say, I will reach a B2 level in Spanish at the end of the year), but also think of your goal as how much you will be able to improve every day/week/month. For example, in the case of language learning, this could mean having a goal of learning at a certain rate, and keeping a certain routine every day. At the end of the road, even if you didn’t manage to reach your position-based goal, if you still stuck to your velocity-based one, you will have succeeded and will have avoided severely losing motivation."

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