Running

long day

I like to go running in the park, particularly after a long day at work.

A 'long day' can refer to one that keeps you moving for many hours, or one that is stressful in some way.  Notice the following:

1. Waking up early and doing things after work make some long days during the week.
   
2. It was fun, but it was a really long day.
   

get some exercise

When you've been inside for the whole day, it's really nice to go outside in the fresh air and get some exercise.

'Get some exercise' is just another way to say 'do exercise.' Notice the following:

1. After a long day in a car, it feels really nice to get some exercise.
   
2. Can you take the dog for a walk? She needs to get some exercise today.
   

feel good

After the run is finished, you feel so good.

When something 'feels good,' it makes your body feel stronger, more relaxed or more comfortable. Notice the following:

1. Yoga makes people with back problems feel good.
   
2. It feels so good to stretch after a long day on my feet.
   

worthwhile

You really feel good about yourself, because you know you've done something worthwhile.

Something that is 'worthwhile' is valuable or rewarding.  You get some kind of reward from the effort you put in it. Notice the following:

1. His mother told him to find something more worthwhile to do with his time.
   
2. I've been working on this for hours. It just doesn't seem like it will be worthwhile.
   

treadmill

Sometimes, I like to go to the gym and I like to run on the treadmill.

A 'treadmill' is an exercise machine that is used for running and walking.  It has a belt on it that goes around and around so you can run in one place. Notice the following:

1. I usually run on the treadmill, but I'm trying to change up my routine.
   
2. Unless you have good music or a book, running on a treadmill can be really boring.