When the prepositional phrase comes at the end of the sentence there are no commas. They went swimming during the summer months. During the summer months, they swam in the lake of many colors . Yelling at people , many bosses feel like they are in control. Running around the block made him feel great.
Happy songs are good at lifting a person's depression .
To run around the block was his big goal. The stoplights were placed to allow people a safe crossing . The special medicine stopped his desire to scratch the poison ivy . By adding information or clarifying a specific point, they modify the entire sentence. The hamster having finished lunch, it was ready to sleep.