Here are some other ways to say it, depending on the context:
* "I'm feeling well."
* "I'm feeling great."
* "I'm doing well."
* "I'm in good spirits."
* "I'm feeling happy."
It's important to note that "je me sens bien" can also mean "I feel comfortable" or "I feel at ease." In those cases, the English translations would be different:
* "I feel comfortable."
* "I feel at ease."
* "I'm relaxed."