If you feel you are low on energy and are about to give up on going to the gym today, don't. Still go and do that lazy jog on the treadmill for 20 minutes and come back.
The first few minutes of exercise give you the best bang for your buck. So its not all waste.
Mentally you still get to count that you hit the gym. May be you will see friend or wave at a stranger.
Consistency does not require you to be 100 percent everyday. You won't be. The slight push you give today on the machine will help you be prepped and push harder tomorrow.
A lot of days you would do well in the gym start as ‘meh’ days before you get in there.