Can You Become a Runner, or Are You Genetically Doomed?
Is it possible that running is a sport that will never develop for some people?
I spoke once with a triathlete who had running as her weakest discipline. She was training for her first half-marathon and had started running many more miles than ever before. Her frustration was that it never felt easier, which wasn't helped by her assumption that long runs of 8-10 miles would instantly translate to more comfortable or maybe even faster 5k times.
She incorporated hill runs, intervals on the treadmill, and striders/sprints at the end of her runs. It still felt tough, like her body was tired. She tried to eat as healthy as possible to fuel the machine, but no matter what she did she struggled with running.
She was looking for any suggestions for those who want to run happy, but just feel genetically doomed.
It is definitely true that some people are more genetically programmed to be good runners than others, and that only a small percentage of them actually go out and run (but that's another subject...)
If your body is feeling tired while you are running, then there is probably something wrong with your training that isn't right for you. The first place you might want to look is at your diet.
Food, Diet & Running
In this particular case, she said that she was eating a healthy diet, which is always good, but when was she eating her meals? Do you eat anything before your runs so that you have some fuel while you are working out? Are you eating anything shortly after your workouts so that your body will have the fuel it needs to repair your muscles rather than just shutting down and leaving you sore? What foods are you eating before & after?
My next thought after singling out food would be that to check if you are over-training.
Overtraining and Hammering Workouts
How fast are you running? How hard are your other workouts during the week?
Are all of your runs some sort of hill workout or treadmill intervals or striders or sprints?
I have quite a few triathlete friends that have burnt themselves out by hammering 6 speed workouts a week (2 swimming, 2 biking and 2 running) plus doing a long run and then wondering why they're so run-down and tired.
Their thinking is that if they use different muscle groups then they are still getting the chance to recover, and when they were younger that might even have been the case but now they are all having to start to slow down a little for at least half of those workouts or else switch up which discipline they concentrate on from week to week.
My first advice here might be to look at your overall schedule to see if you are trying to do back to back hard workouts (even if they are different disciplines) and also to look at whether it might be in your best interest to slow down on your runs.
Rest and Recovery
The third thing, which is very closely related, is how much rest are you getting each week? If you don't recover from your workouts, you can't improve. Recovery is the process of repairing the damage done to your muscles during a workout, and every athlete needs some down time to give their muscles a chance before stressing them out again. That doesn't necessarily mean taking a day off completely, but it does mean that you do need some less intense workouts now and again.
The Effects of Boredom
The last suggestion I have without more details would be to look at where you are running. If you aren't enjoying yourself, then maybe you should try changing things up.
If you are on a treadmill most of the time, try getting outside instead. If you are always on the roads, then try finding some trails to run on. If you usually run alone, join a club and find some running partners (just make sure they aren't too fast for you if you are trying to slow down!)
And in case you were curious, her problem was in fact that she was hammering all of her workouts and not allowing herself enough time to recover and rebuild her damaged muscles.