Years ago, I had the pleasure of running the New York City Marathon. Looking back at that experience, the question arises whether that jog through New York (and all the training that led up to it) was a fulfillment of the Mitzvah of “And you shall guard your souls”, or an exhausting case of teenage time wasting. Let us take a look at some of the writings of our Baalai Mesorah in an attempt to formulate a position on the merit of exercising.
Before we analyze the Halachic attitude towards exercising, we must first ask a basic and sensitive philosophical question: Can one actually prolong or shorten his stay in this world by caring or abusing his body -do we not maintain that Hashem has already determined one’s time of death, and one’s intervention can not alter this pre-destined time? The Tosfoth in Ketuvoth (30a “Hakol”) writes that although we maintain “Hakol Bidai Shamaim, Chutz M’yirat Shamaim,” everything is in God’s control except for one’s Yirat Shamayim, one can in fact, take his life before his pre-determined time if he acts in a reckless and irresponsible manner. This is why, Tosfoth explains, the Gemara prohibits one from walking in a dangerous place. Similarly, the Rambam (Pairush Mishnayot Pesachim Sof Perek Dalet) writes that one who does not seek medical help for his ailment may hasten his own death and die before his prescribed time. This concept of being proactive regarding one’s own health is in line with the Pasuk of V’rapoh Yirapeh, which demands one to heal himself when he is ill, and not wait passively for Divine Intervention.
Regarding the Halachic attitude towards exercising, the Rambam writes in Hilchot Daiot (4:1,2,14): “It is Darchai Hashem to have a healthy body since it is most difficult to develop spiritually when one is sick. Therefore, one must refrain from activities and foods, which harm the Guf (body), and perform activities that strengthen the body. Exercise and a proper diet help preserve the Guf, while idleness and an unhealthy diet harm the Guf.” It appears quite evident from the Rambam that attending to one’s physical health certainly is a Mitzvah. This Mitzvah is not a typical Halachic activity like Kiddush or Brachot that is extensively dealt with and clearly delineated by the Poskim. This Mitzvah is more subjective and must be treated on a case-by-case basis; an individual born to a family with heart disease may need a different regimen then one born to a family with no history of such complications.
Although it is clear that a healthy lifestyle, which includes a well-balanced diet and proper exercise, is a Mitzvah, it is crucial that we approach this topic with the proper Torah perspective. The Rambam writes the following in the fifth Perek of the Shmoneh Perakim, his introduction to Pirkei Avoth:
“Man needs to subordinate his soul’s powers to one goal, namely, spiritual perfection. He should direct all of his actions, both when at motion and when at rest, and all of his conversation toward this goal so that none of his actions are in any way frivolous, I mean an action not leading toward to this goal. He should make his aim only the health of his body when he eats, drinks, sleeps, is awake, and is in motion or at rest. The purpose of his body’s health is that the soul finds its instruments healthy and sound in order that it can be directed toward spiritual growth. On the basis of this reasoning, he would not aim at pleasure alone, choosing the most pleasant food and drink, and similarly with the rest of his conduct. Rather, he would aim at what is most useful. If it happens to be pleasant, so be it, and if it happens to be repugnant, so be it. On the basis of this reasoning, the art of medicine is given a very large role with respect to the virtues, the knowledge of God, and attaining true happiness.”
Maintaining one’s body is clearly a most important means towards spiritual perfection; therefore, one must never be too focused on the means, and lose sight of his true goals. The lion’s share of one’s activities must certainly be in the spiritual arena – Talmud Torah, Chessed, characteristic refinement, etc. – while the Guf is maintained as a Kli, a vessel, which is essential for his pursuit of spirituality. Obviously, one with this goal would spend much more time and energy on the latter. Even when spending time on the Guf, one may try to be involved in the spiritual, such as exercising while listening to a Shiur, riding a stationary bike while reading a Saifer, etc,
Regarding our original question about running a marathon, as we said, one’s specific regimen is subjective and should be discussed with a doctor, so we cannot say what is appropriate for each individual. However, one must be wary about spending so much time on his physical well-being, and must challenge himself with questions regarding values and priorities. Maybe after one’s visit to the doctor, for guidance regarding matters of the body, one should meet with his Rabbi for guidance regarding matters of the soul!
 Regarding Divine Providence and human intervention see Yoma 85b, Rabainu Chananel Chagiga 4b, Rambam Shmoneh Perakim chapter 8, Moreh Nevuchim 2:48, Ramban Milchamot Hashem, Sanhedrin 74b, Radvaz 3;444, Shulchan Aruch Orach Chaim 618:1, Alshich Braishit 37:18, Maharal Chidushai Agadoth Rosh Hashana 16a, Ohr Hachaim Braishit 37:21,Birkai Yosaif Yoreh Daiah 336,Tashbaz 1:51, Malbim Shmuel Bet 24:10, The Lonely Man of Faith by Rav Soloveitchik end of chapter 8, Yechaveh Daat 1:61. However, see also Emunoth V’daioth 4:5,Chovoth Levavoth Shaar Bitachon chapter3, Ibn Ezra Mishpatim “V’rapoh Yirapaih,” Ramban Vayikra 26:11, Tosfot Baba Bathra 144b “Hakol Bidai”, Iggeret Hakodesh #25 by the Baal Hatanya, Shaim Olam by the Chafaiz Chaim chapter 3.