How do you feel about receiving gift cards as gifts?

I am a horrible gift giver. (To be fair, I am also a horrible gift receiver.)

My best friend’s birthday is coming up, and the only things I can think of to get her are in the general category of gift cards (e.g., paying for her yoga membership for a month).

Is this tacky? Especially as a best friend, I feel like I should be getting something more heartfelt.