help?

I don't know where to post this at all.. but I'm just looking for advice

my brother left for training for the air Force. and my mom really wants me to write him a letter to show support since he doesn't really have much from anyone else. but the problem is I'm not close with him we never ever got along. I am proud that he's doing something and not turning into our dad but I have NO idea what to write in this letter. I feel bad but we just never got along. 🤷

so I'm really in need of what to put in this letter . please 🙁

and I don't want to send a crappy letter just saying I'm proud of you. because that's all I can think of 🙁