Do you have to refrigerate butter spray?

The short response is no.

Butter does not have to be refrigerated; however certain restriction should be taken if butter is to be left un-refrigerated. If kept at normal room temperature and covered, butter should be semi-solid, soft and ready to serve. However if temperature if higher than 70 F,  butter could go rancid.

Push up require upper body strength, so weight-training exercises such as shoulder press, curl ups and dead lifts would improve your ability to perform proper push ups.