Nope work capacity is not the issue. You just still have beginner strength levels like sub 2 plate bench and its time for you to hit up a proper progression model.
Due to manual labour and generally what you’ve posted in the past your work capacity is actually significantly above average
Read the article, like Jim says can do sprints/prowler/ HIIT sessions on off days if want to keep building “pure work capacity”
Bottom line 5/3/1 plain works have seen 100+ responses like this below over the years…
