I'm looking for some first hand responses from people that have added in cardio and core work to their routine and the positive and negative effects they noticed from doing so.

Since gaining a lot of size I've noticed my agility and stamina has decreased. I need size for my job (security) but also to be able to use it aswell. I'm going to start training mma once a week plus doing c/c on that day aswell along with adding a c/c only day. But I'm concerned it will affect my size gains as I will lose a day of strength training a week. Thoughts?