To achieve anything of significance in sport, you must master "The Training Triumvirate". This "triumvirate" (or "trioka" if you prefer) is composed of three cornerstones; training, nutrition, and recovery.
All are crucial to an athlete's progress, but as the system is stressed and during periods of growth, each cornerstone may be stretched and come into sharper or softer focus. Outside stressors play the role of a centrifuge - bumping, spinning, and pulling the trioka in different directions. The triangle can become easily distorted if the sides are not girded by a center filled with inner peace, knowledge, drive, experience, and work capacity.
In the following illustration, a trainee has honed in on his/her training. Notice how the corresponding interior angle sharpens to attack, while the others become less acute. It is common to see new trainess fall into this pattern of behavior, as they have great enthusiasm for a new program or athletic endeavor.
The next picture represents an athlete who has given great attention to training and recovery, but not as much attention to diet.
The last triangle represents an individual who spends an exorbanant amount of time, money, and effort on training and diet, yet largely ignores recovery. Notice how unstable this triumvirate has become - left unchecked, it is only a matter of time before it collapses, no matter how solid the insides are. Overzealous teens who train to failure everyday and eat enough to fuel a small team of athletes and polish it all off with a protein shake, yet pull all-night video game marathons are an example of this pattern. It is common to see this pattern during athletes' peak training periods as well; purposeful overreaching that will be followed by a taper - it should be planned and monitored carefully.
Over the long haul, striking a consistent balance among the three corners of the triumvirate will yield the best results.