06/28/2012 at 09:00 AM EDT
Since giving birth
to daughter Maxwell Drew
May 1, Jessica Simpson
has swapped maternity dresses
for workout gear
, and teamed up with Weight Watchers
to get back in shape.
And she says she's feeling better – not feeling pressure.
"Just so everyone knows...Weight Watchers hasn't put ANY pressure on me!" she Tweeted
. "I'm trying to be as healthy as I can be for myself and I feel great!"
The new mom, 31, isn't stressing about the scale, either.
"It would be nice to feel comfortable in a bikini, but that's not my goal," she previously told PEOPLE
. "I just want to fit into jeans!"
For Simpson, "life has completely changed" since welcoming baby Maxwell, 8 weeks, her first child with fiancé Eric Johnson
"From how I sleep to what I think about," she told PEOPLE
in May, "Maxwell has definitely taken over everything."