I don't have energy for exercise when I feel tired
This is a challenge especially for people with the inflammatory and autoimmune types of arthritis when fatigue and low energy can be common symptoms.
You do need to pace yourself to avoid a potential ‘crash and burn’ scenario but only time and experience will teach you when to completely kick back and rest and when to exercise at a lower intensity than normal because you are feeling tired.
It may help you to know that exercise encourages your brain to release endorphins, a ‘feel good’ neurochemical that boosts your mental health, decreases your sensitivity to stress and pain, and can make you feel happier.
It seems counter-intuitive but think about expending some energy to enjoy more energy.