Whether you’re in the middle of a hard training session or setting a long term goal it’s important your expectations are not too high. You need to be realistic and make goals achievable or have the sense to say ‘I can’t lift this weight just yet.’
Over training or trying to complete a lift that is beyond your skill level and strength isn’t going to help you in the long term. You’re more likely to get injured or feel like you have failed when you may have had a really productive session up to that point.
Unless you are competing in a sport or competition you shouldn’t compare yourself to anyone else. All the training and goals you set should help you progress and not have a negative impact. If you don’t hit a short term goal it’s not a problem but be honest with yourself: Did you put the work in? If you fail a medium term goal then you need to look at changing something up. If you fail a long term goal then it’s more than likely you were unrealistic at the very start. Don’t set unachievable targets.