Chapter 9 of the Mesilat Yesharim discusses various matters that detract from enthusiasm (zeal!) The Ramchal tells us that such things as seeking the comforts of the body, hating effort and loving physical delights will detract from one’s being able to become enthusiastic in one’s holy activities in life. These all bring a person to great laziness!
Those who seek the comforts of life will not be able to gain in growing – at least spiritually – in one’s life. The person who wishes to get ahead in matters of holiness must learn to be satisfied with the general physical wellbeing of his life in order to be able to focus on more important matters. These matters deal with the study of Torah and the fulfilment of Mitzvot. We are here as workers – serving God – in this physical world. But in return, we will see that ultimately when we return our souls back to God at the end of 120 years, that the efforts we had put in into our spiritual affairs in this world were well worth the rewards that we will receive then.