Knowing that "practice is the only secret recipe for improving" is painful and blessing at the same time. It is painful because I cannot practice properly to satisfy myself. It is a blessing because I am focusing on my inner self after many years. So, I am here to get some advice and help to figure out my problems.

Main Topic

I have doing competitive programming for the last two years. I could not improve much because of my lack of practice. I have been trying to practice since 2020, but I am facing problems consistently during my practice sessions. My problems are,

• I cannot solve problems or think about problems after one and two hours of intense thinking, but I can spend time on one problem for an infinite amount of time. In another word, I can try or hold a problem for a long time(even months), but I cannot think or brainstorm more than an hour at once.
• I am mentally tired during my training session most of the time. If I do it after waking up from sleep morning, I think very clearly. But after an hour or two hours, I cannot even think of any brainstorming work and I get fully distracted. It will take 7 or 8 hours to recover, and sometimes a day.

So, I believe, if I last at brainstorming for a large amount of time during a session, I can improve much. How can I increase mental strength to last many hours(7-8 hours together) of practice at one session?

Many thanks for your concern. If you have any suggestion, advice or solution, please let me know. I will be thankful to you.