Early Bird Catch The Worm?
This is a great example of why we're all different, some of us can train at 6am and feel rejuvenated, energised and setup for the day. Which is great, keep this part of your routine!
For others, it just doesn't agree with their body clock.
You're not being lazy. In fact, strength training performance can range from 3-15% between morning & evening workouts, proving just how people can benefit from training at different times.
There are many factors that would contribute toward this, such as the above, time constraints and how you're fuelled for the session.
Optimal Training Time
If we're talking optimal, without 'life' being a major factor then your optimal training time will be aligned with your Circadian Rhythm, Once your body has depleted itself of Adenosine (sleep drive) during sleep, you will feel more awake and alert and for some, it might be later in the morning for others.
When training in the afternoon your core body temperature is at it's highest, meaning you're better prepared for exercise as well as more sunlight exposure too. Sunlight sends a signal to the pituitary gland which releases hormones such as cortisol and serotonin and suppresses the production of melatonin meaning you'll feel less sleepy and more awake.
It's no coincidence Olympic world records are set during the day at these peak times.