Your training is meant to be challenging in order for it to elicit the response needed for your goals. The idea of the training for putting on muscle, getting stronger and/or losing fat is that it is difficult enough to create a stimulus for your body to adapt to. This will mean it gets hard sometimes and that is the idea, as it is what will help you make progress.
From this adaptation and forced change comes results and progress, alongside the more detailed things like training variables and recovery which allow you to train hard and not get injured or burn out too quick.
Your training will most likely be periodised, which means it is split up into phases that cater towards a certain aspect. For example a powerlifter might have a 12 week competition prep:
2 weeks general physical preparation
4 weeks hypertrophy
4 weeks strength focus and begin to peak
2 weeks to peak, taper and deload for competition
So what we know is that periodisation comes with different focuses of training and delving further this means varying exercises, volume, frequency, intensities, stresses and without a doubt some days where everything will just feel heavy and sluggish.
If these days occur, the best thing is to just to keep the head in the right state of mind and complete your training to the best of your ability. Don’t pack it in early or let emotion cloud your lifting if things don’t move your way. Far easier said than done as I’m sure anyone trying to make progress knows but, the positive and confident mindset is the better route to take.
With this being said, don’t be a hero. If you are trying to push through an injury, or really feel your form taking a massive hit, I think it is more mature in that case to leave training for another day.
But my overall point is training is not meant to be easy (on the whole) when you are pushing for progress. This is not saying go heavy all the time, or that you should feel awful all the time, it is simply a reminder that you should expect a challenge and should stay in the right mindset in order to get it done.
Being able to push through tougher sessions or stages of training will make you a better lifter overall and you will see a real benefit from having the right mindset.
Feel free to contact me with any feedback, questions or enquiries at: firstname.lastname@example.org or interact with me on Facebook at “Ben Glasscock Powerlifter” and/or Instagram where I post pretty much every day: @blgstrength or a link here. Coaching is available at very reasonable rates too, get in contact via email, Facebook and/or Instagram, I’d love to hear from you!