KEEP UP YOUR MOTIVATION.
1- SET GOALS These should be realistic, achievable and meaningful- for instance, hitting your workout 3 times per week, or achieving a PB weight or try a completely new class and keep things fresh.
2- TRACK YOUR WORKOUTS. This reminds you how far you have come when the going gets tough. You could also track the weights you lift in class or the cadence you use on a spin bike.
3-PERFECT IS THE ENEMY OF GOOD. Not every workout will be your best. Not every week will be your most active. Dont get disheartened, what matters is sticking to a progressive training routine over time. Keep showing up and you will get back on track and start to see improvements.