The mantra "No Pain. No Gain", is a flawed belief.
Firstly, it assumes that you are the centre of the world; that the outcome is contingent on how much effort you put in. (when oftentimes, success is pushing through strategic pieces, and letting nature and chance lead the charge)
Secondly, that attitude is devoid of all respect for oneself; doing so will expose oneself to serious chronic injury.
Instead, the mentality should be: I need to do what I need to do, and need to deliver the required results. I can push through pain. I can't fight through injury.
You are your own boss (and if you're not, start fixing your life). Expectations are malleable.
I'm pretty confident that the moment people give themselves a hospitable mindset to pursue their goals, they will adopt the mentality that pain is to be expected ... not deserved, not earned. It just is. It's just there. Say hello.
The keyword is "hospitable". Hospitable isn't "comfortable". It isn't "painful". It's "enlivening" -- promoting life.
And that's a long way of saying, just do what you fucking need to do. And stay safe.