Can I do that?

I’ve almost decided to entrr the university to take a bachelor degree, but I became a bit less confident because of my recent performance. Last month, before visiting Hokkaido last week, I was very fine and confident I could study in early morning like 5am. But after coming back, I cannot wake up early, cooking is not easy, feel tired every day so couldn’t treat my daughter well. Is it because of the weather? probably yes. Then summer will come next year too, so not sure if i could study constantly.....

In addition, I am very tired!!!! Not sure what to do. I have been researching a lot of things lately, so I may need to take a rest now...