The "Spider-Man: No Way Home" star says he knew he had to make a change starting back in 2019, "I felt like I could barely walk upstairs without being out of breath, and this one day I kind of just saw myself without a shirt on and it was just ridiculous ...”

Jacob says COVID-19 and the lockdown that followed really helped him to work on himself, hiring a trainer and hitting the gym 6x a week for hour-and-a-half sessions.

Not only did Jacob hit the gym hard, but he says his girlfriend introduced him to a plant-based diet as well ... and the results have been huge for him.