Putnam preparation resources

I am a freshman with some competitive math experience (USAMO qualification) who just recently decided to study for the putnam. I tried doing many of the most popular books such as putnam and beyond and problem solving strategies, however I have honestly found these books very tedious and challenging. They are not very similar to high school competition questions, and I often find myself stuck and I just give up.

Are there any other resources that might be a bit more introductory, or do I just have to persevere through the difficulty and try harder? Any advice is appreciated.