Name what they did
Specific thanks feel warmer than broad praise. Mention the dinner, the introduction, the lift, the advice, the gift, the listening ear, or the effort they made.
Say what changed
Add one sentence about the impact. Maybe it made a hard week easier, helped you feel seen, saved you time, or gave you confidence.
Close simply
A thank-you card does not need a grand finish. A short line such as "I really appreciate it" often lands better than trying to make the message ornate.