How can I solve this relationship issue?

My wife and I have an excellent relationship. We are good at solving problems and negotiating when we have differences of opinion/goals/desires/etc. But, after almost 8 years together, I have never been able to get across to her how much I need her to follow through on the things she says she is going to do.

Example 1: She has been saying she is going to stop smoking for over a year. I stopped, when we said we were both going to, but she never did. As much as I abhor it, its her choice. I just wish she’d stop saying she is going to do it if she’s not.

Example 2: I asked that she get a few things accomplished while she is on winter break. She’s been off 2 weeks and has yet to finish even 1 task, but she keeps saying she’ll do it.

Example 3: She says she’‘ll give the cat her pills or clean the litter boxes, but I ask her later or the next day if she did and she says no. If she’d just tell me she doesn’t have time, I’d do it, with absolutely no animosity, but when she says she’ll do it and doesn’t, then it doesn’t get done.

This happens consistently, and it seems no matter what I try, after 8 or so years, it’s still happening.

Any insight? Have you dealt with this? Any suggestions on how to handle this?