my coach has been working me on the heavy bag for 45 minutes every session. ther heavy bag makes your fighting "space", wortk for you. by using the heavy bag, you can learn how to keep moving because the bag is always moving. always burn out at the 30 second bell. jag and cross till the 30 second bell. than you will see the benefits of working the bag. do it as much as you can. trust me.