Developing the muscles of discipline is more important than maintaining any particular disciplined schedule or routine. We all have periods of productivity and ruts of malaise, that is normal. Even Imaan increases and decreases; I think it is a fiction that most people can actually adopt a highly disciplined lifestyle for long, extended periods.

The important thing is to cultivate the capacity for discipline and detachment, whereby you can switch off your responsiveness to your own urges, wants, and interest in your comfort and indulgence. Detach your mind from the tasks you are performing. You can hone this capability through mundane, repetitive, monotonous activities; whether work-related, fitness-related, or even household tasks. Once you have built these 'discipline muscles' you will be able to activate them whenever necessary, and this is crucial for men to be able to do.
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https://www.youtube.com/watch?v=nsFIQ4L-kkc