I think it is a good step in the right direction. One thing you can do is to switch up your speed while you are in your 30 minute workout period. Instead of staying at 4.0 mph for the whole time, try speeding up for 30 seconds, then slowing down for 90 seconds or 2 minutes, then repeating this cycle 3 or 4 times.
You can get a much more intense and beneficial workout in the same time frame.
5 min. @ 3.0 mph to warm up
30 seconds faster @ 5.0 mph
90 seconds @ 3.5 mph (recovery phrase)
Then again - 30 seconds @ 5.0 mph / 90 sec. @ 3.5 mph
Repeat this 4 times
Then jog @ 4.0 mph for 15 minutes
Cooldown @ 3.0 mph for 5 min.This is just a example, you can adjust it to whatever works best for you at the fitness level you are currently at
. The key is to vary your speed to keep your body constantly adjusting and working hard.
Remember to stretch your leg muscles afterwards, slow stretching calves, quads, hamstrings.