I've been running long distance for about 10 years and one of the hardest decisions a long distance runner makes in preparing for a race is in choosing a goal time or pace. It requires you to honestly and objectively evaluate your physical and mental preparedness to undertake a big race like a marathon or an ultramarathon typically before you've even started training. Overestimate, and simply finishing will become one of the hardest and most painful things you'll ever do, and underestimate and you'll likely end up with a disappointing time. In my opinion the first step is to figure out what time of person you are. Start by asking yourself if you are likely more cautious or perhaps a bit more on the cocky side and perhaps more aggressive in estimating your abilities. If you've never done a marathon before then, it's in some ways a bit easier, because you'll pretty much just need to see how your training plays out and evaluate based on some of your longer workouts. If you're an experienced runner you need to consider some of the following questions:
What are your previous times and were those good honest efforts?
Were the past race results good indicators of your capability? (Easy and comfortable finishes typically aren't good signs, although they could be)
Do you ever run faster paces/times in training than in your races? (Is this because you choose conservative goals or due to performance issues on race day?)
Are you able to work at or above race effort in training for shorter distances? (You should be able to run faster than your goal race pace for an hour or more)
How frequently do you fall apart during your hard workouts? (Never and always are not good answers to this question.)
Are you choosing a goal that is significantly faster than your training runs? (A yes here could mean you're being a bit aggressive)
The other thing to keep in mind is that your goal pace is often selected at the beginning of your training cycle in order to set paces for your workouts. Depending on how your training is going, you may need or want to adjust your pace midway through your training. This is normal, but don't readjust too frequently, as 1 or 2 good/bad workouts is really not enough information to make a good assessment. I'd say every 4 weeks it is worth looking at the data (definitely keep a log, ideally garmin, strava, movescount, etc) and figuring out if you should readjust your target race pace. Make small adjustments and gauge how each workout feels. The easy runs should feel easy and the hard workouts should feel hard, sometimes real hard. If you easily complete all your workouts, then your pace is too slow. If you never complete any, then it is too fast.
I'm now about 4 weeks away from Boston, and have about 8 weeks of training in so far. The first 6 weeks felt very hard. I was always tired, my legs remained sore for several days after my hard workouts and my paces were far slower than I would have liked. I was struggling big time to perform workouts based on my target race pace. Nonetheless I forged ahead, one workout at a time, trying not to obsessively compare workouts to the ones performed in previous years. Strava is a blessing and a curse for this reason. All your benchmarks and workouts are automatically compared for you and remind you how you're doing compared to other years. I've met a few people who somehow manage to stay fit year round, but for most of us this just isn't possible. Instead, we ride the ebb and flow of the seasons and, planned or not, allow ourselves a break to recover before undertaking a period of high intensity training to peak for a race or a season of races. I fall into the latter category, intentionally giving my body a break for a few months of the year. The effect of this however is that awful feeling of building back your fitness and struggling to do what was once easy. And as you become fitter you must figure out when you're going to reach your desired peak or if you're going to reach it.
I'm currently at a point where I'm re-evaluating my goal race pace. I have 2 more weeks before my taper begins. The past 2 weeks have been incredible. I'm not nearly as tired, I'm easily hitting my target paces and I'm not nearly as sore after my workouts so I know I'm getting close to being at peak fitness because I get a clear feeling. This feeling happens at a different point in my training each year, but if I put the work in, it always seems to come. I like to compare it to fishing. Every time you're reeling the line back in and the lure snags on a weed/rock/stick, you get a quick and short moment where it feels like a fish, but any fisherman will tell you, that that feeling is quite a bit different than when you actually hook a real fish, and that "you'll know when it happens, just wait for it". The two feelings (e.g. I think I'm ready VS I'm actually ready) are easily confused at first, but it doesn't take too long to tell the difference, and the more experience you have the easier it is to judge. The caveat though, is that with fishing, you know for sure within a few minutes. With running you never really know until race day plays out.
I also should point out that the past 2 weeks also coincides with the arrival of my new Liv9 recovery blends, supplements and vitamins, which helped speed up the process. My next post will cover what Liv9 "geared to you" products I'm using this year, why I'm using it and how I think it's helping.