Don’t be afraid to take a day off. If you’re motivated but just tired, listen to your body and take a break. It’s telling you something. One day off is better than seven days off being sick. Fitness takes place when you rest and recover, not when you’re out riding. There’s a balancing act between recovery and training that needs to take place, but you get my point.
If being tired isn’t a problem for you at the moment then plan which days you’ll take off at the beginning of the week. Look at the weather forecast on Sunday evening and see what the trend is. If the end of the week is looking miserable then try to get in all you can at the beginning.