Dont have the energy to do cardio, what can I do?

I'm finding myself depleted during my workouts. Either I can do cardio first and nothing else or do some weights first and absolutely no cardio after, why is this and what can I do?

I don't take energy drinks or pre workouts as it gives me the jitters and makes me a little manic

Dont have the energy to do cardio, what can I do?
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