I suffer from that paralysing combination of over-commitment and perfectionism so I struggle with motivation.
I don’t have any magic bullets for the problem of flagging motivation but I do know that my own thoughts drive my emotions and that negative emotions undermine my good intentions. The secret seems to be to regard all tasks as neutral and avoid emotional overlays or implications. Another observation of what works is to start small and achievable and build on the positive energy.
For me it’s an ongoing struggle…Fortunately, I have great critique partners to help me back on track.