I agree with Marykb.  I'm 63 and I don't use a heart rate monitor because my blood pressure medication is going to keep my heart rate low anyway.  I'm currently training for a couple half marathons and my last long run was 11 miles at an average 9:23 pace and I ran it in 1:43;24.  Not too shabby for an old guy, huh?  I do use a garmin gps watch now but I didn't have one until very recently.  The basic truth behind endurance and speed is this...... You won't increase endurance by continually running the same distance and hoping it will happen and you won't increase speed by continually running the same pace an hoping to magically get faster.  It takes time and work.  Long runs and Fartleks.  One long run and one speed work session each week along with your base runs.  Of course, you need to finish c25k first.  Just keep at it and you'll get there.

you should probably recalibrate your Nike+.  I had to run on treadmill due to rain and my Nike+ is perfect but i did recalibrate mine on a track at high school.  They do not recomment you recalibrate on treadmill.

Hi Lucy!  Although everything you said there may be exactly right, I still stick by my opinion that beginning runners just don't need to make it all that complicated.  This is my opinion, of course, but I feel like unless you are running competitively - that is a whole different story in which case you will have a coach or a trainer - then you usually can't go wrong by listening to your body.  I think anyone, if they pay attention, knows if their HR is about to max out.  Its not like its going to happen without your noticing it, right? (DISCLAIMER: Of course this doesn't apply to someone who is badly out of shape and/or has a medical condition in which an elevated HR can be dangerous.)

When I mentioned speedwork earlier, I did qualify that by saying it is a whole different scenario, in other words, not something a new runner has to worry about right now.  But even a beginning runner can add brief spurts of intensity.  During an otherwise steady paced run you can run up a hill or you can "run as fast as you can to the next mailbox" (which is also known as a "fartlek") and those will briefly bump up your HR.  That is a good thing, because it builds strength, and strength will build endurance (AND speed). The whole idea about "staying in the aerobic zone" kind of smacks of the old myth about the "fat burning zone" where people let themselves be convinced that lower intensity exercise trumps higher intensity exercise.  There are some facts that are taken out of context which are used to make it sound like ramping up the intensity is counterproductive.  Not true! 

My whole point about running, for the casual recreational runner, is to MAKE IT FUN!  I hear so many people say, "I hate running but I do it anyway".  Well I don't hate running and I never have because I listen to my body and do what feels right.  Even without knowing any of the complicated physiology behind it, I have trained myself from someone who was completely non-athletic and out of shape to someone who can run a half marathon.  I have averaged about 1000 miles/year and 6-8 races a year for several years so although my mileage isn't high, it is steady and consistent.  (Sadly I can't train my arthritic knees to carry me much farther at this point!)  I am a middle aged, slightly overweight grandmother.  If I can do this without making it complicated, then I believe anyone can!

D,

I have never been a devotee of lots of tech when I am running, so all of the heart rate monitor and Garmin talk leaves me in the lurch.  When I first re-entered the running field (last year) my major mistake was in setting my pace too high when I started out.  That was cured by setting up a good running mix on the music player with a fairly relaxed starting track to help me establish a sustainable pace.  If I had a Million Dollars by Bare Naked Ladies works well for my starting track.  After a few minutes into the run, as systems warm up a bit, I mix some (moderately) higher paced music in, which helps me add in some of the up tempo bursts that others have written about.

I have to ask; where are your eyes when you are running?  If you get your eyes are focused on the ground directly in front then your mind tends to focus there too.  Look down range and you will be able focus on reaching some point in the distance.  As you approach that intermediate goal, congratulate yourself on reaching it, and set/negotiate another goal.  Aim for just over the top of the grade, the bend in the trail or road, the next intersection, etc.  You get the flick.  View a long run as a collection of short runs stacked end to end and perhaps you will not fixate on the overall distance, clearing your mind to just enjoy the run.

Whatever works for you, stay with it and have fun.