Something that I hear from so many people is that they cannot start this or that activity because they are not fit enough.
To me that just sounds like an excuse to maintain inertia.
From my personal perspective, when I started my own triathlon training years ago, I was clinically obese. Did that stop me. No it didn’t. All I did at the start was substitute my run workouts for additional bike rides till my weight dropped to a level where my joints would be able to handle the impact of my running.
It worked – and I got into shape through the process of my activity. I did not wait till I was in shape before starting.