That's a great question, JM. There is no magical answer because we are all unique in how we deal with change. We turtle or embrace it head-on.
I am by no means an expert - I am trained in psychiatric nursing but have not practiced in it - but having been through significant lows in my personal life , I always focussed on attainable short term goals; those that didn't seem so insurmountable that they would throw me into a funk.
I used the term 'one step' to get me through tough times: it may be one step forward or backwards. The forward steps were progress; the backward ones were viewed as important ones to move forward eventually - but not hinder me. They were frustrating but necessary learning moments.
Honestly, those ebbs gave me better wisdom to move forward than the highs.
I think I just wrote a short form! LOL!!