To be successful it is important to learn to physically relax.
Take time off each week. Only work five or six days per week, and then rest on day seven. Studies have shown you are more productive in the five or six days you work if you take one or two days off completely, rather than working seven days straight.
On your day off, don’t use the time to catch up on work. Simply relax, spend time with family, friends, watch television, exercise, do nothing that requires any mental effort on your part. Ensure you close down for at least one full day per week, you will benefit from it enormously.