As much as consistency is important, and as much as the most important behaviors happen when they are built into your life, built into your routine, such that exceptions never show as an excuse or get in way, days of rest are also necessary. You might say, how come then? Isn’t this going to break the flow of repetition, possibly create a new pattern of rest and couch potato-ization? We have to deal with ambiguity in many domains, professional and personal, and days of rest are of them, just like days of food over-indulgence help make life more social, fun, and a good use of time.
Rest does need to be a pattern, with its own frequency and trigger points. Naturally, if we develop an injury, the tearing that happened in muscle tissue, ligament or bone will need extensive time to heal, which means at the very least not exerting this area.
It could take the form of cross training: some muscle groups and parts of your body rest – the injured or tired ones – while other parts perform activity at higher intensity. Cross training a great form of partial rest. For runners who develop shin splints, for example, as a result of too much ground impact, acqua running provides relief. Your leg muscles still need to work extra hard, especially with the resistance from water up to your waist, but the impacts are significantly diminished. Another form of cross training is to simply stop running and perform push-ups, which will not make shin splints get worse while still giving you the benefit of upper body muscle.
You can also get stronger with days of rest, in this case nearly full rest. If you exerted muscles during endurance sessions, you likely experienced glycogen store depletion. Recall that glycogen is the carbohydrate fuel stored inside your muscles, and one of the main sources of energy your body uses during exercise. It takes up to a week to fully replenish these glycogen levels, which is why marathon runners stop long runs a few days before the event. This allows their energy stores to be completely full when they show up on race day. Full rest also means that micro tears that happen on an ongoing basis and we may not feel as painful, because they are a small and repair themselves quickly, can have time to heal. Most athletes take a day of rest during the week, to accomplish exactly this. You can of course still do small things, like going with your day, showing up at work, walking lightly, taking public transportation. A day of rest doesn’t need to be a day in bed, unless you are seriously wounded or ill.
Lastly, doing hard physical work, as rewarding as it may be, can lead to tiredness and loss of motivation. Because the body may at some point become unable to overcompensate by self-repair while continuing strenuous training, a day or two off can not only be good physiologically, it can be reinvigorating psychologically. Rest, for the active person, replenishes motivation so that you are quickly itching to go back again to a workout.