Slow down to speed up
Sometimes it is better to slow down in order to be able to speed up. We need frequent pauses in order to replenish our lost energy during the day. Thinking, prioritizing, taking decisions, meetings, conversations with all kinds of people—all these can be exhausting. It's up to us to follow the signals of our body and to be aware of the environmental influences it is exposed to.
Creating textual and visual content, writing code and applying styles when we are already tired isn't the best use of our time. Once we start, it may be very easy to lose sense of the effort we put into a task. Doing more then leads to diminishing returns. It's probably a good idea to start resting before we reach the state of total exhaustion. Or maybe we shouldn't allow exhaustion at all, working in well-defined, cyclically alternating time slots of work and pause. But to achieve this, we need to have a reminder and be ready to disable it every time it is on, being disciplined enough to do what is needed during that time slot. Software can help us to manage our time, but it can't help with managing our commitment. We can try out different programs to see whether they will work for us. I found Free Alarm Clock to be useful for me as it allows to plan the whole day. It brings a popup (optionally accompanied by a calm music) at certain time points during the day, which can be closed by simple press of the spacebar or Enter keys. If you liked the way Benjamin Franklin organized his day, this software can help you come to something similar. But if your schedule changes every day, it can quickly become tiring to manage all alarms. In this case you are probably better without any software. But having a working style based on a variable effort is probably not a good idea.
When we slow down, we have an opportunity to evaluate how we have done so far or simply to get feedback from others, which helps us improve our work. We could also come up with ideas we haven't previously considered while being at work. It's interesting that if we find a way to experience how slowly time is moving (maybe through meditative music or something else) while thinking about or seeing something inspiring, we can motivate ourselves to move much faster once we are back to work. Hard problems can often be solved after we had the time to reflect on the various alternatives without impulsively picking the first that came to our mind.
We can also slow down without really having a rest, maybe when our mind is busy, but with less demanding tasks. It's very important to be able to free it of anything work-related during a pause. For this, it can be useful to walk in nature, to talk to interesting new people, to visit new places or generally to do radically different things than we are used to. Sometimes, our best ideas are born when our world is completely shaken. Then we can reevaluate our current situation and apply new urgency to it.