Edith Cowan University research revealed that muscle strength benefits are seen with consistent, short exercise sessions. Participants performing a three-second eccentric bicep contraction thrice weekly saw strength improvements. Daily 20-minute exercises might be more beneficial than a single 2-hour weekly session. Regularity, even in short durations, is key to health benefits.
Caloric restriction, or eating less calories than you burn off. Yeah, it is long, but it's a good watch.
TL;DW: eat less calories than you burn off, eat more protein, and lift weights or do calisthenics (body weight exercises like pushups, etc).
Thanks