Consider the unpredictable
Do you know what makes it really hard to stick to any kind of routine? Suffering from fatigue and low energy after your first rounds of working out. If you notice that you have some sort of day-to-day unpredictability, consider taking a flexible approach to exercise, choosing a gentle stretch session rather than an aerobics class.
Or, you could go for a strength routine instead of pilates if you feel extremely energized. My point is that you should match your workouts with your daily mood rather than sticking to a rigid schedule. You will definitely end up working out more than just rushing into something difficult that will only exhaust your body.