Cardio is often an element of fitness that people ignore, but it's crucial to incorporate these kinds of exercises into your routine if you want your endurance to increase.
I know there's a misconception that you have to spend hours on the treadmill or elliptical when you're doing cardio, but even If you only have 30 minutes, you can do this quick and intense sprint workout!
High intensity interval training (HIIT) burns maximum calories in a short period of time as you complete hard intervals in quick bursts. If you have a little more time, you can increase the warmup and cooldown periods.
I’ve included the speeds I used for my workout today – modify your speed to your fitness level. My warmup and resting pace was about 60% of my maximum effort, and my sprinting pace (for 10 repetitions of 1 minute) was about 80% of my max.
Note: This will require the use of a treadmill.