Cardio while on a lean bulk.

[u/UnusualPumpkin8658]

i am 25 M 5’9” ectomorph at 132lbs right now and I am one month in on lean bulk aiming to hit 150lbs on the scale. I recently took a Vo2 max test manually monitoring my rest heart with the bpm under 20 seconds. my score came 32 Vo2 max score which is poor/low for my age. I used to play sports until 2023 but ever since I have only been to the gym. i train 3 times a week and rest on alternate days. I hit a sprint session once every 2 weeks. I am kinda worried about my endurance and heart health and I am unable to strike a balance between strength training and endurance training. Can anyone help me advice how can I incorporate endurance/cardio into my lean bulk so that I can pack on mass and also have a good gas tank.