Assuming you have a wristwatch, the most basic method is to note a time on your wristwatch, touch your pulse and start counting, riding one-handed. When you have to stop, notice the time and the nynber you counted to, and write them down. Next step up, go digital, but see what Walgreen's, Osco Drugs or Cosco sell. All of these wll be cheaper, though less capable than an Oura.